Casting Defects and Heat Treatment of Aluminium Bronze

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Patent Search and Analysis Report (PSAR) Reports
“Casting Defects in Aluminium Bronze and
Enhancing the Mechanical Property By Heat
Trreatment.”
Submitted by
Tirth S. Upadhyay (Enrollment No.: 100870119007)
Vamit R. Patel (Enrollment No.: 100870119019)
Abhishek A. Tantia (Enrollment No.: 100870119058)
Nirav A. Patel (Enrollment No.: 110873119007)
In partial fulfillment for the award of the degree
of
BACHELOR OF ENGINEERING
in
MECHANICAL ENGINEERING
Parul Institute of Technology
P.O: Limda, Ta.:Waghodia, Dist.: Vadodara
Gujarat Technological University,Ahmedabad,
MAY, 2014

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DECLARATION
We hereby declare that the PSAR Reports, submitted along with the Project
Report for the project entitled “Casting Defects in Aluminium Bronze and
Enhancing the Mechanical Property By Heat Treatment.” submitted in
partial fulfillment for the degree of Bachelor of Engineering in Mechanical
Engineering to Gujarat Technological University, Ahmadabad, is a bonafide
record of the project work carried out at Parul Institute of Technology, Limda
under the supervision of Mr. Prashantsingh Tomar Sir and that no part of any
of these PSAR reports has been directly copied from any students’ reports or
taken from any other source, without providing due reference.
Name of The Students Sign of Students
1. Tirth S. Upadhyay
2. Vamit R. Patel
3. Abhishek A. Tantia
4. Nirav A. Patel

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CERTIFICATE
This is to certify that the PSAR reports, submitted along with the project entitled
“Casting Defects in Aluminium Bronze and Breaking of Material During
Machining.” has been carried out by Tirth Upadhyay, Vamit Patel, Abhishek
Tantia & Nirav Patel under my guidance in partial fulfillment for the degree of
Bachelor of Engineering in Mechanical Engineering 7th Semester of Gujarat
Technological University, Ahmadabad during the academic year 2013-14. These
students have partially completed PSAR activity under my guidance.
Internal Guide Head of the Department

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PHASE 1
Gujarat Technological University
TeamId : 130008137
ProjectTeamMember
Enrollment Number Student Name College Name Branch Name
100870119007 Tirth Upadhyay Parul Institute Of
Technology, Limda
Mechanical
Engineering
100870119019 Vamit Patel Parul Institute Of
Technology, Limda
Mechanical
Engineering
100870119058 Abhishek Tantia Parul Institute Of
Technology, Limda
Mechanical
Engineering
110873119007 Nirav Patel Parul Institute Of
Technology, Limda
Mechanical
Engineering

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ACKNOWLEDGMENTS
Our first and sincere appreciation goes to Mr. Bhavesh. G. Mewada, for being our senior supervisor,
for all we have learned from him and for his continuous help and support in all stages of this project.
We would also like to thank him for being an open person to ideas, and for encouraging and helping
us to shape our interest and ideas.
We would like to express our deep gratitude and respect to Miss. Alice D’souza whose advices and
insight was invaluable to us. For all we learned from her.
In addition, we would like to thank Mr. Prashantsingh ToMar for accepting to be our supervisor in this
project and for his vast knowledge in the field of Metallurgy, which helped us to address our research
question. Also, thanking him for accepting to be the internal guide.
We would like to thank our family, especially our parents for always believing in us, for their
continuous love and their supports in our decisions. Without whom we could not have made it here.
In the end, we would like to thank Mr. Raghvendra Joshi and Cyprum Casting for providing us with
all necessary equipments and the support whenever we required. It also provided us the instruments
that we used for this research.
We would extend my regards to all those who directly or indirectly were involved in this project and a
warm regards to all my other group members without whom this project would never have been
possible.

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Project: IDP
Definition: Casting defects in AluminiumBronze and
Enhancing its Mechanical Properties by Heat Treatment
Company: Cyprum Casting,MakarpuraG.I.D.C.,Vadodara.
ABSTRACT
Aluminium bronze is a type of bronze in which aluminium is the main alloying metal added to copper,
in contrast to standard bronze (copper and tin) or brass (copper and zinc). A variety of aluminium
bronzes of differing compositions have found industrial use, with most ranging from 9% to 14%
aluminium by weight, the remaining mass being copper; other alloying agents such as iron, nickel,
manganese and silicon are also sometimes added to aluminium bronzes.
The company makes aluminum bronze bush used to prevent wear in shafts. The work piece of
composite material of aluminum bronze having composition of 5% Nickel, 5% Iron, 10% Aluminum
and 80% Copper. It is prepared by the metal casting process. The Aluminum used belongs to the grade
C95500. The material undergoes breakage during machining and due to which the company faces high
rejection. Our motto is to try to reduce the reduction rate and resulting in high profitability to the firm.
We tried to achieve the result by varying the composition of aluminium in aluminium bronze but by
conducting various respective testing we observed that aluminium content should be increased but
limited up to 14% in aluminium bronze.
Secondly we tried to change the composition of alloying elements like iron, nikel and manganese
whose results are mentioned later in the report but we didn’t get satisfying output. We also tired
changing the pouring temperature and came to the conclusion that it should be maintained in the range
of 1000 to 1300℃. Then we checked for the pouring height of the metal but it didn’t play a major
role in avoiding oxide formation. Then studying the microstructure which we got through SEM testing
we learnt that the formation of slag in the molten metal resulted into the oxide formation in the
casting. To avoid it we added composition of flux into molten metal which results in floating of slag
above the molten metal and which made it easily removable before poring it into the mould. The
casting produced with the use of flux resulted in reduction of oxide formation drastically and the
material didn’t break during machining.
We also tried to study the effect of heat treatment on various mechanical properties and tried to
improve the properties of aluminium bronze alloy which resulted in the increase of its application.

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INDEX
1 Introduction 13
1.1 Introduction to Aluminium Bronze 13
1.2 Composition of Aluminium Bronze 15
1.2.1 Classifications of Different Grades of Al-Bronze 16
1.2.2 Classification of Cast and Wrought Alloys : 16
1.2.2.1 Cast Aluminum Bronze: 16
1.2.2.2 Wrought Aluminum Bronze: 17
1.3 Properties of Aluminium Bronze 18
1.4 Applications of Aluminium Bronze 18
1.4.1 Foundry Products 18
1.4.2 Wrought Products 20
1.5 Casting Techniques of Aluminium Bronze 20
1.5.1 Sand Casting Process 20
1.5.2 Gravity Die Casting 21
1.5.3 Low-Pressure Gravity Die Casting 21
1.5.4 Pressure Die Casting 21
1.5.5 Thixocasting 21
1.6 Objective 21
1.7 Plan of Work 22

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2 Litereture Review 23
2.1 Effect of Composition on Properties 23
2.2 Oxide Formation in Aluminium Bronze: 25
2.3 Methods for Reduction of Oxide Formation 27
2.3.1 Cleaning and Designing the Melt 27
2.3.2 Determination of insoluble Non Metallic Impurities 28
2.3.3 Addition of Fluxes 29
2.3.4 Melt Temperature 30
2.4 Heat Treatment 31
2.4.1 Procedure for Heat treatment 31
2.5 Summary 33
3 Charge Preparation 34
3.1.1 Charge Preparation 34
3.1.2 Calculations 35
4: Melting and Casting Practice 36
4.1 Basic Equipments 36
4.2 Preparing of Auminium Bronze Alloys (AB1) 40
4.3 Preparing of Nickel-Aluminium Bronze Alloy (AB2) 41
4.4 Slag Removal 41
5: Heat Treatment 44
6 Testing and TestReports 45
6.1 Scanning Electron Microscope (SEM) Study: 45
6.2 Energy Dispersive X-ray Spectroscopy (EDAX) 50
6.3 Hardness testing: 58
6.4 Tensile Testing: 59

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7 Conclusion 61
7.1 Reduction in Oxide Formation: 61
7.2 Heat Treatment 63
8: References 64

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List of Table
Figure
No. Name of Table
Page
No
1 Composition of Aluminium Bronze Alloy 16
2 Products formed by Wrought Aluminium- Bronze 17
3 Oxide Formation in Copper Alloys 26
4 Dimensions of Test Bar 34
5 Composition for AB1+2% 52
6 Composition for AB1 53
7 Composition for AB2 54
8 Composition for AB2+2% 55
9 Hardness Of Cast Sample 57
10 Hardness of Heat Treated Sample 58
11 Harness Comparison of Cast Sample and Heat treated Sample 58
12 Dimension of Test Specimen 59
13 Tensile Strength of Cast and Heat Treated Sample 60
14 Hardness Comparison of Cast and Heat Treated 63
15 Tensile Strength of Cast and Heat Treated Sample 63

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List of Figure
Figure
No. Name of Figure
Page
No
1 Centrifugally cast nickel-aluminum bronze high-pressure
flange for a sub-sea weapons ejection system.
19
2 Wear rings for a large hydro turbine, centrifugally cast in
nickel-aluminum bronze, alloy C95800
19
3 Continuous cast gear-wheel blanks, aluminum bronze, alloy
C95400
20
4 Unetched x 100 26
5 Degassing 28
6 Fluxes for efficent metal treatment 29
7 Logas 50 degassing agents and DEOX Tubes for degassing &
deoxidation
30
8 Permanent Mould as a Cast Test Bar 34
9 Standard Sample With all Dimensions 34
10 Crucible 36
11 Graphite Crucible with Charge Particle 36
12 Pit Furnace 37
13 Pattern 37
14 Mould 38
15 Gating System 38
16 Tongs 39
17 Sand Muller 39
18 Heating of Carge Material in Pit Furnace 40
19 Removal of Slag 42
20 Final Casting 42
21 Machining after Casting 43
22 Setupof SEM 45
23 Test specimens 46
24 Line Diagram of SEM 47
25 AB1 As Cast 47
26 AB1 Heat Treated 48
27 AB1+2% As Cast 48
28 AB1+2% Heat Treated 48
29 AB2 As Cast 48

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30 AB2 Heat Treated 49
31 AB2+2% As Cast 49
32 AB2+2% Heat Treated 49
33 Information system in SEM 50
34 Initiation of X-Ray 51
35 EDAX study for AB1+2% 52
36 EDAX study for AB1 53
37 EDAX study of AB2 54
38 EDAX study for AB2+2% 55
39 Test Specimen 56
40 Brinell Hardness Tester 57
41 Heat treated samples 59
42 As cast samples 59

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CHAPTER-1 INTRODUCTION
1.1 INTRODUCTONTO ALUMINIUM BRONZE
The aluminium bronzes are a family of copper-base alloys containing approximately 5% to
11% aluminium, some having additions of iron, nickel, manganese or silicon. They include
alloys suitable for sand casting, gravity die-casting and for the production of forgings, plate,
sheet, tube, strip, wire and extruded rods and sections. Compared with other copper alloys, the
higher strength of the aluminium bronzes is combined with excellent corrosion resistance
under a wide range of service conditions.
Aluminium bronzes are the most tarnish-resistant copper alloys and show no serious
deterioration in appearance and no significant loss of mechanical properties on exposure to
most atmospheric conditions. Their resistance to atmospheric corrosion combined with high
strength is exploited, for example, in their use for bearing bushes in aircraft frames.
Aluminium bronzes also show low rates of oxidation at high temperatures and excellent
resistance to sulphuric acid, sulphur dioxide and other combustion products and are, therefore,
used for the construction of items exposed to either or both these conditions. For example,
aluminium bronzes are used very successfully for inert gas fans in oil tankers. These operate
under highly stressed conditions in a variable but very corrosive atmosphere containing salt-
laden water vapour, sulphurous gases and carbon.
No engineering alloy is immune to corrosion. Corrosion resistance depends upon the
formation of a thin protective film or layer of corrosion products which prevents or
substantially slows down the rate of attack. The aluminium content of aluminium bronzes
imparts the ability to form, very rapidly, an alumina-rich protective film which is highly
protective and is not susceptible to localised breakdown and consequent pitting in the
presence of chlorides. Aluminium bronzes are, therefore, very resistant to corrosion by sea
water and probably find more use in sea water service than in any other environment.
Virtually all metals and alloys in common use are susceptible to some extent to crevice
corrosion, i.e. accelerated attack within or just at the edge of areas shielded by close proximity
to other components or by deposits on the surface. Crevice corrosion in service is particularly
objectionable when it takes the form of pitting or severe surface roughening on shafts or valve
spindles in the way of bearings or seals.
Any crevice corrosion of aluminium bronzes, however, takes the form of minor selective
phase
dealloying which results in little reduction of strength and practically no impairment of
surface finish. Aluminium bronzes are, therefore, very widely used for pump shafts and for
valve spindles - situations where pitting corrosion in crevices makes stainless steels, for
example, unsuitable.

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A form of selective phase dealloying of aluminium bronzes commonly known as
'dealuminification' which caused some concern some years ago is no longer a significant
problem. This type of attack, similar to the dezincification of duplex brasses, results in
selective dissolution of the principal alloying element (in this case aluminium) from one phase
of the alloy leaving a residue of porous copper which retains the original shape and
dimensions of the component but has little strength. By controlling the composition and, for
the alloys of high aluminium content, the cooling rate from casting or working temperature,
metallurgical structures are ensured that will not suffer dealuminification to anysignificant
extent under any normal conditions of use.
Metal failures in service are often the result of the combined influence of corrosion and
mechanical factors, the most common being stress corrosion, which occurs under the
simultaneous action of high tensile stress and an appropriate corrosive environment, and
corrosion fatigue which occurs under cyclic stressing in a corrosive environment. Brasses, for
example, show high susceptibility to stress corrosion in the presence of even small quantities
of ammonia, and austenitic stainless steels suffer stress corrosion cracking in hot chloride
solutions.
High resistance to stress corrosion cracking is an important reason for the use of aluminium
bronzes by the British Navy for underwater fastenings. High tensile brasses, formerly used for
this service, were very liable to fail by stress corrosion but stress corrosion failures of
aluminium bronze fasteners have proved extremely rare.
High resistance to corrosion fatigue is essential for marine propellers and it is principally for
that
reason that most large propellers are made from nickel aluminium bronze. This material is
quite
outstanding in resistance to corrosion fatigue in sea water, being much superior to high tensile
brass or to stainless steels. Manganese aluminium bronze, which is also used for large
propellers, also has high corrosion fatigue strength though somewhat inferior to nickel
aluminium bronze.
Turbulent water flow conditions can cause local erosion of the protective films on which
alloys
depend for their corrosion resistance and result in localised deep attack by a combination of
corrosive and erosive action. The corrosion/erosion resistance of the aluminium bronzes is
substantially higher than that of the brasses and similar to that of 70/30 copper-nickel which is
generally recognised to be one of the alloys most resistant to this type of attack.
At higher water flow rates, such as exist in pumps and on some areas of marine propellers,
formation and collapse of vapour cavities in the water can produce very high local stresses
leading to cavitation damage. The resistance of alloys to cavitation damage generally
increases with their resistance to corrosion fatigue and with their ability to reform protective
films rapidly on the metal freshly exposed by cavitation erosion. The advantages of
aluminium bronze over most other alloys in these respects have already been mentioned and it
will be no surprise, therefore, that aluminium bronzes show exceptionally high resistance to

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cavitation damage. This is an important feature in their use for marine propellers and the
principal reason for their use for impellers in high duty pumps.
However, the soundness of the casting has a very significant bearing on resistance to
cavitation
erosion and impingement attack, and maximum resistance cannot be expected from a casting
produced by bad foundry practice.
One further property of aluminium bronzes should be mentioned in this general survey of
their
corrosion resistance. In most practical engineering situations different metals or alloys are
used in contact with each other in the presence of an electrolyte such as sea water or fresh
water. In these circumstances the possibility of galvanic action, causing accelerated attack on
the less noble metal, can be very important. Aluminium bronzes are slightly more noble than
most other copper alloys and slightly less noble than the copper-nickel alloys but the
differences are too small to cause significant galvanic effects. Monel, stainless steel and
titanium are all considerably more noble than aluminium bronze but it is found in practice
that, providing the exposed area of the more noble metal does not greatly exceed that of the
aluminium bronze, very little acceleration of corrosion of the aluminium bronze occurs. It is
for this reason that aluminium bronze tubeplates are used in condensers with titanium tubes
[1].
1.2 COMPOSITION OF ALUMINIUM BRONZE
In addition to aluminium, the major alloying elements are nickel, iron, manganese and silicon.
Varying proportions of these result in a comprehensive range of alloys to meet a wide range
of engineering requirements.
There are four major types of alloy available:
a)Single-phase alpha alloys:
The single-phase alpha alloys containing less than 8% of aluminium. These have a good
ductility and are suitable for extensive cold working. CA102 is typical of this type. Alloys
containing 3% iron, such as CA106, are single phase up to over 9% aluminium
b)Duplex alloys:
The duplex alloys containing from 8% - 11% aluminium and usually additions of iron and
nickel to give higher strengths. Examples of these are the casting alloys:
AB1 CuAl10Fe3
AB2 CuAl10Fe5Ni5
Wrought alloys: CA105 CuAl10Fe3 and CA104 CuAl10Fe5Ni5 DGS1043

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c)Copper-aluminium- silicon alloys:
The copper-aluminium-silicon alloys have lower magnetic permeability:
Cast AB3 CuAl6Si2Fe
Wrought CA107 CuAl6Si2
DGS1044
These are mainly alpha alloys and have good strength and ductility.
d)Copper-manganese-aluminium alloys:
The copper-manganese-aluminium alloys with good castability developed for the manufacture
of propellers.
CMA1 CuMn13Al8Fe3Ni3
We will be focusing mainly on Duplex alloys i.e. AB1 and AB2 types basically in our
project[2].
1.2.1 Classificationsofdifferent grades of al-bronze:
Grades Sr.no
Approx. alloy composition(%)
Al Fe Ni Mn Cu
AB1
1 9 3 - -
rest
2 13 4 - -
AB2
3 10 4 5 1
4 11 4 4 -
5 8 3 2 18
Table no 1: composition of aluminium bronze alloy
1.2.2 ClassificationofCastand Wrought alloys :
1.2.2.1CastAluminum Bronze :
Aluminum bronze castings are produced by the recognized techniques of sand, shell,
permanent mold (low-pressure die), ceramic, investment, centrifugal and continuous casting.
The size of castings ranges from tiny investment cast components to very large propellers
weighing 70 tons. One of the very attractive characteristics of aluminum bronzes is that, due
to their short cooling range, they solidify compactly, as do pure metals. This means that,
provided defects are avoided, the metal is inherently sound, more so than alloys such as
gunmetal (tin bronze, UNS C90500) which may be porous unless cooled very rapidly.
The alloy's short freezing range means that adequate feeding is required as the metal
solidifies. It is also essential to prevent the aluminum oxide dross on top of the liquid metal
from becoming entrapped in the castings during pouring. Avoiding internal defects therefore
requires a certain degree of care, although foundries with the required expertise routinely

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produce castings of very high integrity. Because aluminum bronze is often selected for critical
applications, it is important that casting be well designed so as to achieve best results.
Consultation with an experienced founder is essential at a relatively early stage of design
development. Publications are available that are helpful in the initial design work and give a
good basis for consultation between the designer and the founder.
Many duplex alloy castings may be heat treated to improve the microstructure of the alloy,
giving better corrosion resistance and higher strength for only a slight reduction in ductility.
The treatment recommended is to soak at 1220°F (660°C) and cool in still air. The time at
temperature depends on casting size and section thickness but is on the order of two hours.
This treatment is used only for the most critical of applications.
1.2.2.2 Wrought Aluminum Bronze:
A wide variety of wrought products are made in aluminum bronze alloys, including forgings,
rod, bar, section (profile), flat, sheet, strip and plate, filler rod and wire. An indication of this
variety is given in Table.
Table no 2: Products formed by Wrought aluminiumbronze
Material can be chosen from the compositions that are available but manufacturers or
distributors will advise the most suitable alloy for selection. Billets from which wrought
products are made continuously to ensure freedom from entrapped oxide defects, which
would carry through to the final product. These billets are then hot worked by conventional
methods such as extrusion, rolling or forging. Rolling, extrusion and rotary forging produce
sections that are to final or near final dimensions and reduce the need for costly machining.
This provides very useful design flexibility. Forgings are produced either freehand in simple
shapes and to relatively wide tolerances, or in closed dies to close tolerances if the quantity

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required justifies the initial cost of the die. Hot pressing, stamping and other methods are used
to produce flanged shafts, nuts and bolts[3].
1.3 PROPERTIESOF ALUMINIUM BRONZE:
 Excellent strength, similar to that of low alloy steels
 Excellent corrosion resistance, especially in seawater and similar environments, where
the alloys often outperform many stainless steels
 Favorable high temperature properties, for short or long term usage
 Good resistance to fatigue, ensuring a long service life
 Good resistance to creep, making the alloys useful at elevated temperatures
 Oxidation resistance, for exposure at elevated temperatures and in oxidizing
environments
 Ease of casting and fabrication, when compared to many materials used for similar
purposes
 High hardness and wear resistance, providing excellent bearing properties in arduous
applications
 Ductility, which, like that for all copper alloys, is not diminished at low temperatures;
 Good weld ability, making fabrication economical
 Readily machined, when compared with other high-duty alloys
 Low magnetic susceptibility, useful for many special applications, and
 Ready availability, in cast or wrought forms[4].
1.4 APPLICATIONS OF ALUMINIUM BRONZE:
1.4.1FOUNDRYPRODUCTS
 Impellers Bearings
 Propellers Gear selector forks
 Shafts Synchronizing rings
 Pumps & valves Non-sparking tools
 Water cooled compressors Glass moulds
 Tube sheets & other heat
 exchanger parts
 Pipe fittings
 Marine environments
 ornamental articles
 Channel covers Rudders & Propeller brackets
 Gears & Gear blanks Die-cast components

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 Deep drawing dies Continuous cast bar & shapes
 Pickling equipment Centrifugal castings
 Rolling Mill equipment
 Bushes
Fig1. Centrifugally cast nickel-aluminum bronze high-pressure flange for a sub-sea
weapons ejection system.
Fig2. Wear rings for a large hydro turbine, centrifugally cast in nickel-aluminum
bronze, alloy C95800.

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Fig3 . Continuous cast gear-wheel blanks, aluminum bronze, alloy C95400.
1.4.2 WROUGHT PRODUCTS
 Drop forgings Chain
 Tube sheets Impellers
 Tubes & Shells Compressor blades
 Pressure vessels Shafting
 Reaction & Distillation vessels Gears
 Pipe work Non-sparking tools
 Wear plates Non-magnetic equipment
 Springs Masonry fixings
 Bearings Rod, bar & shapes
 Fasteners Free hammer forgings
 Valve spindles
 In addition, aluminum bronzes are extensively used as metal-sprayed or weld-deposited
surfacing materials, generally over steel substrates, in order to provide wear, corrosion and
sparking resistance[5].
1.5CASTINGTECHNIQUES OF ALUMINIUM BRONZE:
1.5.1 SAND CASTING PROCESS:
The sand casting process is used predominantly in two fields of applications i.e. for
prototypes and small-scale production on the one hand and for the volume production of
castings with a very complex geometry on the other. For the casting of prototypes, the main
arguments in favour of the sand casting process are its high degree of flexibility in the case of
design changes and the
comparably low cost of the model. In volume production, the level of complexity and
precision achieved in the castings are its main advantages[11].

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1.5.2 GRAVITY DIE CASTING:
When higher mechanical properties are required in the cast piece, such as higher elongation or
strength, gravity die casting, and to a limited extent pressure die casting, are used. In gravity
die casting, there is the possibility of using sand cores. Large differences in wall thicknesses
can be favorably influenced with the help of risers. Cylinder heads for water-cooled engines
represent a
typical application[10].
1.5.3 LOW- PRESSURE GRAVITY DIE CASTING:
In the low-pressure gravity die process with its upward and controllable cavity filling, the
formation of air pockets is reduced to a minimum and, consequently, high casting quality can
be achieved. In addition to uphill filling, the overpressure of approx. 0.5 bar has a positive
effect on balancing out defects caused by shrinkage. The low-pressure die casting process is
particularly advantageous in the casting of rotationally symmetrical parts, e.g. in the
manufacture of passenger vehicle wheels[8].
1.5.4 PRESSURE DIE CASTING:
Pressure die casting is the most widely used casting process for aluminium casting alloys.
Pressure die casting is of particular advantage in the volume production of parts where the
requirement is on high surface quality and the least possible machining. Special applications
(e.g.vacuum) during casting enable castings to be welded followed by heat treatment which
fully exploits the property potential displayed by the casting alloy[8].
1.5.5 THIXOCASTING:
In addition to conventional pressure die casting, thixocasting is worthy of mention since heat-
treatable parts can also be manufactured using this process. The special properties are
achieved by shaping the metal during the solid liquid phase. Squeeze-casting is another
casting process to be mentioned; here, solidification takes place at high pressure. In this way,
an almost defect-free microstructure can be produced even where there are large transitions in
the cross-section and insufficient feeding[8].
1.6 OBJECTIVE:
 Melting and Casting of aluminium bronze.
 Studying the causes for oxide formation.
 Studying of the material by changing the composition and adding fuxes.
 To study the effect of aluminium on mechanical and environmental properties like
hardness, wear resistance, tensile strength and corrosion resistance of aluminium bronze.
 Characterization of as cast treated and heat treated aluminium bronze samples.

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1.7 PLAN OF WORK:
 CHARGE PREPARATION
 MELTING AND CASTING PRACTICE
 SAMPLE PREPARATION
 CHANGING THE COMPOSITION AND ADDITION OF FLUX
 HEAT TREATMENT

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CHAPTER 2 LITERATURE REVIEW:
The review of research papers conducted to aid in this dissertation work is presented here in five
sections. The first section discusses the papers reviewed related to effect of composition on properties
of aluminium bronze alloys . The second section reviews papers related to Oxide formation in
aluminium bronze. In the third section papers which have provided useful insight for casting
techniques of aluminium bronze are reviewed. The fourth section presents papers reporting methods
for reduction of oxide formation in aluminium bronze alloys. The fifth section discusses the scope and
objectives of the work conceived for this dissertation work.
2.1 EFFECTSOF COMPOSITION ON PROPERTIES:
From Copper Development Association [2] has worked on the change in properties and
behavior of aluminium bronze by varying the composition of the aluminium bronze. He
arrived to the conclusion that the mechanical properties of aluminium bronze depend
primarily on aluminium content. Alloys with up to about 8% aluminium have a ductile single
phase structure and are the most suitable for cold working into tube, sheet, strip and wire. As
the aluminium content is increased to between 8% and 10% the alloys are progressively
strengthened by a second, harder phase which makes them more suitable for hot working and
casting. Above 10% an even greater strength and hardness is developed for specialised wear
resistant applications.
The other major alloying elements also modify the structure to increase strength and corrosion
resistance: iron improves the tensile strength and acts as a grain refiner; nickel improves proof
stress and corrosion resistance and has a beneficial stabilising effect on the metallurgical
structure; manganese also performs a stabilizing function.
Z. Ahmad and P. Dvami[6] have worked on the change in properties and behavior of
aluminium bronze by manganese to the aluminium bronze and find out that if manganese, at
about 13%, is the major addition in a series of manganese aluminium bronzes with aluminium
levels of 8 - 9%. Their foundry properties are better than the aluminium bronzes and they
have good resistance to impingement and cavitation, as well as being heat treatable to low
magnetic permeability. They have excellent welding properties.
J. O. Edwards and D. A. Whittaker[7] have worked on the change in properties and behavior
of aluminium bronze by adding iron, nickel and manganese to the aluminium bronze and had
following conclusions:
 The addition of iron up to 1% improves the mechanical properties mainly due to its effect
on grain refinement. However the addition of iron is limited up to 5.5%.Above 1.2% the
tensile strength and hardness are improved but its ductility gets lowered.
 The addition of nickel to an alloy containing iron has a beneficial effect in modifying the
stable structure.
 The most important effect of manganese is in improving the corrosion resistance of an
aluminium bronze, the addition of magnesium is sufficient up to 6%. The main drawback
is that aluminum bronze with low manganese addition is susceptible to corrosion when
the addition exceeds 11% a fully stable structure is obtained resulting corrosion properties.

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From the Aluminum Casting Alloys_english_PV_2012_11_30 [8] which have researched
on the change in properties and behavior of aluminium bronze by adding silicon, iron,
copper, nickel, manganese, magnesium, zinc and titanium to the aluminium bronze and
the following conclusions can be drawn
Silicon
 Improves the casting properties
 Produces age-hardenability in combination with magnesium but causes a grey color
during anodisation
 In pure AlCu casting alloys (e.g. Al Cu4Ti), silicon is a harmful impurity and leads to hot
tearing susceptibility.
Iron
 At a content of approx. 0.2 % and above, has a decidedly negative influence on the
ductility (elongation at fracture); this results in a very brittle AlFe(Si) compound in the
form of plates which appear in micrographs as “needles”; the seplates act like large-scale
micro structural
 separations and lead to fracture when the slightest strain is applied
 At a content of approx. 0.4 % and above, reduces the tendency to stickiness in pressure die
casting.
Copper
 Increases the strength, also at high temperatures (high temperature strength)
 Produces age-hardenability
 Impairs corrosion resistance
 In binary AlCu casting alloys, the large solidification range needs to be taken into account
from casting/technical point of view.
Manganese
 Partially offsets iron‘s negative effect on ductility when iron content is > 0.15 %
 Segregates in combination with iron and chromium
 Reduces the tendency to stickiness in pressure die casting.
Magnesium
 Produces age-hardenability in combination with silicon, copper or zinc; with zinc also
 self-hardening
 Improves corrosion resistance
 Increases the tendency towards oxidation and hydrogen absorption
 Binary AlMg casting alloys are difficult to cast owing to their large solidification range.
Zinc
 Increases strength
 Produces (self) age-hardenability in conjunction with magnesium.

25
Nickel
 increases high-temperature strength.
Titanium
 increases strength (solid-solution hardening)
 produces grain refinement on its own and together with boron.
2.2 Oxide Formation in Aluminium Bronze:
M Hansen and K Anderko[9] conducted their work to try to reduce the oxide formation in
copper alloys by taking copper–oxygen system, the procedure and conclusion is explained
below:
The copper-oxygen system is an example of a simple eutectic system. The high-conductivity
copper used for the vast majority of electrical applications generally contains from 0.01 to
0.05% oxygen but may contain up to 0.1%.
Solidification commences with the formation of nuclei on cooling below the liquidus
temperature (on line AC). As the temperature falls, these nuclei, which are essentially pure
copper, proceed to grow in size, causing the liquid to become richer in oxygen. The
composition
of the liquid follows the liquidus AC until, at the eutectic point C, the liquid remaining
between
the primary grains solidifies at constant temperature to form the eutectic composed of α and
Cu2O. It will be seen from the diagram that the oxygen content of the melt controls the
amount
of residual liquid solidifying with eutectic composition; the relative proportions of primary
and
eutectic constituents therefore gives a good indication of the alloy's composition.
Until the advent of modern continuous casting plant for high-conductivity copper, porosity
was
always visible in the microstructure, being an important feature of what was known as tough
pitch copper. During fire-refining, air is injected into the molten copper to oxidize impurities.
As a result, oxygen is absorbed by the copper. Hydrogen is also picked up in the furnace,
particularly during the subsequent reducing or 'poling' operation, and co-exists in equilibrium
with the oxygen. On solidification, this equilibrium is disturbed, the oxygen and hydrogen
reacting together to form steam which becomes entrapped in the casting. By carefully
reducing the oxygen content to a controlled level, the volume of the steam cavities may be
made to Counteract the natural solidification contraction of the metal and so produce wire
bars or cake with a level top surface ideal for subsequent fabrication.

26
Fig: 4 Unetched x 100
This microstructure consists of irregularly
shaped primary grains of outlined by a
network of and Cu20 eutectic. The
constituent of the eutectic has become
absorbed by the primary grains and is not
visible as separate particles. The large black areas
associated with the eutectic are gas
cavities.
Point A B C D E F G H I
°C 1083 1065 1065 1065 1200 1200 600 -375 -375
O2% 0 0.008 0.39 11.2 1.5 10.2 0.0017 100 11.2
Table no: 3 oxide formation in copper alloys

27
From the Aluminum Casting Alloys_english_PV_2012_11_30 [8] which have worked on the
melt management to reduce the oxide formation in aluminium bronze, we came to know that
during transition from liquid to solid state, the dissolved hydrogen in the melt precipitates
and, on interacting with oxides, causes the well-known problem of micro porosity or gas
porosity. The task of melt management and treatment is to keep oxide formation and,
consequently, the dangers to cast quality within limits.
Here are a few key points to reduce oxide formation:
 Use good quality ingots
 Quality-oriented melting technology and equipment
 Correct charging of the ingots (dry, rapid melting)
 Temperature control during melting and casting
 Melt cleaning and melt control
 Safety measures during treatment, transport and casting
2.3 METHODS FOR REDUCTIONOF OXIDE FORMATION:
2.3.1 CLEANING AND DEGASING THE MELT:
From the Aluminum Casting Alloys_english_PV_2012_11_30 [8] which worked on the
methods to clean the melt we observed that casting alloys consist of effectively cleaned metal.
Since reoxidation always takes place during smelting, and in practice revert material is always
used, a thorough cleaning of the melt is necessary prior to casting.
Holding the aluminium melt at the correct temperature for a long time is an effective cleaning
method. It is, however, very time-intensive and not carried out that often as a result. Foundry
men are thus left with only intensive methods, i.e. using technical equipment or the usual
commercially available mixture of salts.
According to A.W. Tracy which worked on effective cleaning of melt concluded that melt
cleaning is a physical process: the gas bubbles rising through the liquid metal attach oxide
films to their outer surfaces and allow hydrogen to diffuse into the bubbles from the melt.
Both are transported to the bath surface by the bubbles. It is therefore clear that in order for
cleaning of the melt to be effective, it is desirable to have as many small gas bubbles as
possible distributed across the entire cross-section of the bath. Dross can be removed from the
surface of the bath, possibly with the aid of oxide- binding salts [12].
According to J. L. Sullivan, who carried his research on inert gas flushing of melt to clean and
degas the melt we came to following conclusion that, Inert-gas flushing by means of an
impeller is a widely-used, economical and environmentally-sound cleaning process. The gas
stream is dispersed in the form of very small bubbles by the rapid turning of a rotor and, in
conjunction with the good intermixing of the melt, this leads to very efficient degassing. To
achieve an optimum degassing effect, the various parameters such as rotor diameter and
revolutions per minute, gas flow rate, treatment time, geometry and size of the crucible used

28
as well as the alloy, have to be co-ordinate. The course of degassing and reabsorption of
hydrogen is depicted for various casting alloys[13].
According to G. W. Lorimer, F. Hasan, J. Iqbal and N. Ridley; have worked on the methods
of using commercial salts and filters for reduction in oxide formation in casting and
concluded that when using commercially available salt preparations, the manufacturer‘s
instructions concerning use, proportioning, storage and safety should be followed. Apart from
this, attention should also be paid to the quality and care of tools and auxiliary materials used
for cleaning so that the cleaning effect is not impaired.
If practically feasible, it is also possible to filter the melt using a ceramic foam filter. In the
precision casting of high grade castings, especially in the sand casting process, the use of
ceramic filters in the runner to the sand mould has proved to be a success. Above all, such a
filter leads to an even flow and can retain coarse impurities and oxides[14].
FIG 5 DEGASSING
2.3.2 DETERMINATION OF INSOLUBLE NON METALIC IMPURITIES:
The literature survey related to this topic was performed because the non soluble impurities
reacts with gases to form oxides which degrades the melt quality and result in casting defects.
From the Aluminum Casting Alloys_english_PV_2012_11_30 [8] which also carried the
work in determining the insoluble non- metallic impurities in casting by Porous Disc
Filtration Apparatus (PoDFA) method. We can conclude that for determining the number and
type of insoluble non-metallic impurities in aluminium melts, the Porous Disc Filtration
Apparatus (PoDFA) method, among others, can be used. In this particular method, a precise
amount of the melt is squeezed through a fine filter and the trapped impurities are investigated
metallographically with respect to their type and number. The PoDFA method is one of the
determination procedures which facilitates the acquisition, both qualitatively and
quantitatively, of the impurity content. It is used primarily for evaluating the filtration and
other cleaning treatments employed and, in casting alloys production, is utilized at regular

29
intervals for the purpose of quality control. This method is not suitable for making constant
routine checks since it is very time-consuming and entails high costs[8].
Correlation between the hydrogen content and density index in unmodified Al Si9Mg
alloy
2.3.3 ADDITION OF FLUXES:
Accoding to United State, Environmental Protection Agency, "Report on the Corrosion of
certain Alloys",Washington, DC. 20460, July 2001, which worked on reduction in metal
losses and the the oxide formation in casting by the use of proper pouring temperature along
with protective fluxes. We concluded that Metal losses and of alloying elements oxidation
were decreased due to use of proper pouring temperature of alloys with using the protective
fluxes. The best mechanical properties such as ultimate tensile strength and hardness are
found in treated nickel aluminium bronze alloys (T-AB2), due to the effects of fluxes material
such as ( Logas 50 and deoxidizing tubes E3 ) to minimize the casting defects. In addation,
the effects of rise of (Ni and Fe) contents on the improving on the mechanical properties[15].
Auxiliary Materials: - Some additive materials are used such as;
Albral 2:- A calcium and sodium fluoride powder is used as a protective cover for the molten
metal during melting process.
FIG 6: Fluxes for efficent metal treatment

30
Deoxidizing tubes (E3):- These tubes are made of copper and contain a powder of phosphorus
and other elements and are by weight about (25) g used as a deoxidizing material.
- Logas 50:- A small block which is made from a crushing dolomite blocks (CaMg(CO3)2)
and, used as a liquid of sodium silicate as a binder, each block weighs about (50) g[16].
FIG 7: LOGAS 50 degassing agents and DEOX Tubes for degassing & deoxidation
2.3.4 MELT TEMPERATURE:
According to Aluminum Casting Alloys_english_PV_2012_11_30 which worked on the melt
temperature in relation with the separate alloys came to the following conclusions :
 The temperature of the melt must be set individually for each alloy. Too low melting
temperatures lead to longer residence times and, as a result, to greater oxidation of the
pieces jutting out of the melt. The melt becomes homogeneous too slowly, i.e. local
undercooling allows segregation to take place, even as far as tenacious gravity segregation
of the FeMnCrSi type phases. The mathematical interrelationship for the segregation of
heavy intermetallic phases.
 Furthermore, at too low temperatures, autopurification of the melt (oxides rising) cannot
take place
 When the temperature of the melt is too high, increased oxide formation and gassing can
occur. Lighter alloying elements, e.g. magnesium, are subject to burn-off in any case; this
must be offset by appropriate additions. Too high melting temperatures aggravate this loss
by burning[8].

31
2.5 HEAT TREATMENT:
Heat treatment gives users of castings the possibility of specifically improving the mechanical
properties or even chemical resistance. Depending on the casting type, the following common
and applied methods for aluminium castings can be used:
 Stress relieving
 Stabilising
 Homogenising
 Soft annealing
 Age-hardening.
According to P. Brezina; who conducted his work on heat treatment in casting through age-
hardening method concluded that for age-hardening to take place, there must be a decreasing
solubility of a particular alloy constituent in the α-solid solution with falling temperature. As a
rule, age-hardening comprises three steps:
In solution annealing, sufficient amounts of the important constituents for age-hardening are
dissolved in the α-solid solution.
With rapid quenching, these constituents remain in solution. Afterwards, the parts are
relatively soft.
In ageing, mostly artificial ageing, precipitation of the forcibly dissolved components takes
place in the form of small sub-microscopically phases which cause an increase in hardness
and strength. These tiny phases, which are technically referred to as “coherent or semi
coherent phases”, represent obstacles to the movement of dislocations in the metal, thereby
strengthening the previously easily-formable metal. The most important form of heat
treatment for aluminium castings is artificial ageing[17].
2.5.1 PROCEDUREFOR HEATTREATMENT
S ol ut i oni z i ng
( 8 5 0 - 9 0 0 ° C)
( 0 .5 - 2 hr)
W a t e r
que nc hi ng
Ag e i ng
( 3 0 0 - 4 0 0 ° C)
( 2 - 3 hr)

32
1. SOLUTIONIZING:
To bring the hardened constituents into solution as quickly as possible and in a sufficient
amount, the solution annealing temperature should be as high as possible with, however, a
safety margin of approx. 15 K to the softening point of the casting alloy in order to avoid
incipient fusion. For this reason, it is often suggested that casting alloys containing Cu should
undergo step-by-step solution annealing (at fi rst 480 °C, then 520 °C). The annealing time
depends on the wall thickness and the casting process. Compared with sand castings, gravity
die castings require a shorter annealing time to dissolve the constituents sufficiently due to
their finer microstructure. In principle, an annealing time of around one hour suffices. The
normally longer solution annealing times of up to 12 hours, as for example in Al SiMg alloys,
produce a good spheroidising or rounding of the eutectic silicon and, therefore, a marked
improvement in elongation. The respective values for age-hardening temperatures and times
for the individual casting alloys can be indicated on the respective data sheets. During the
annealing phase, the strength of the castings is still very low. They must also be protected
against bending and distortion. With large and sensitive castings, it may be necessary to place
them.
2. QUENCHING:
Hot castings must be cooled in water as rapidly as possible (5-20 seconds depending on wall
thickness) to suppress any unwanted, premature precipitation of the dissolved constituents.
After quenching, the castings display high ductility. This abrupt quenching and the ensuing
increase in internal stresses can lead to distortion of the casting. Parts are often distorted by
vapour bubble pressure shocks incurred during the rapid immersion of hollow castings. If this
is a problem techniques such as spraying under a water shower or quenching in hot water or
oil have proved their value as a first cooling phase. Nevertheless, any straightening work
necessary at this stage should be carried out after quenching and before ageing
3. AGEING:
The procedure of ageing brings about the decisive increase in hardness and strength of the
cast structure through the precipitation of the very small hardening phases. Only after this
does the part have its definitive service properties and its external shape and dimensions.
Common alloys mostly undergo artificial ageing. The ageing temperatures and
times can be varied as required. In this way, for example, the mechanical properties can be
adjusted specifi cally to attain high hardness or strength although, in doing this, relatively
lower elongation must be reckoned with. Conversely, high elongation can be also achieved
while lower strength and hardness values will
be the result. When selecting the ageing temperatures and times, it is best to refer to the
ageing curves which have been worked out for many casting alloys[8].

33
2.6 SUMMARY:
Literature survey is carried out for alloying material of aluminium bronze, causes of the
oxide formation in aluminium bronze by various impurities in the melt , proper selection of
casting process as per application of the alloy, avoiding the oxide formation in aluminium
bronze by various different techniques and the effect of heat treatment in increasing various
properties of aluminium bronze alloy.

34
CHAPTER 3 CHARGE PREPARATION :
3.1.1 CHARGE PREPARATION:
FIG8:PERMANENT MOULD AS A CAST TEST BAR
TABLE NO 4: DIMENSIONS OF TEST BAR
FIG 9 : STANDARD SAMPLE WITH ALL DIMENSIONS

35
3.1.2 CALCULATIONS:
 CALCULATION OF DIAMTER
D = 25 + 2% shrinkage allowances
= 25 + 0.5
≈ 26 mm
 HEIGHT CALCULATION
H = 58 + 2(21) + 2(25) + 2% shrinkage allowances
= 150 + 3
≈ 155 mm
 VOLUME CALCULATION
Volume = ∏/4 * D2 * h
= ∏/4 *(26)2 * 155
= 82252.3 mm3
 DENSITY CALCULATION:
Density of Al-bronze = 7.45 gm/cm3
= 7.45 * 1/1000
= 0.00745 gm/mm3
 WEIGHT CALCULATION:
weight of sample = volume* density
= 82252.3*0.00745
= 612.7gm
≈ 613gm of sample[18]

36
CHAPTER 4: MELTING AND CASTIING PRACTICE:
4.1.1 BASIC EQUIPMENTS:
 CRUCIBLE:
The most widely used method of melting copper in foundries is with crucible furnaces. Gas,
oil-fired or induction furnaces are the most common crucible furnaces used in copper
foundries.
Fig 10: CRUCIBLE
Fig 11: GRAPHITE CRUCIBLE WITH CHARGE PARTICLE
 PIT FURNACE
A furnace made in pit for melting metal during casting process is called a pit furnace.

37
FIG12 : PIT FURNACE
It consists of a cylindrical steel shell, closed at the bottom with a grate and covered with a
removable lid. The shell is lined with refractory bricks from inside. Sometimes the furnace is
completely made in brick. The natural draft of air is used for the metal having low melting
temperature and forced draft with the help of blower is used for metal having high melting
temperature.
To prepare the furnace for melting, a deep bed of coke is kindled and allowed to burn until a
state of good combustion is attained some of the coke is removed to make place for crucible.
The crucible is then lowered into furnace. Metal is then charged in the crucible and the
furnace lid is replaced to give natural draft. When the desired temperature is received the
crucible is removed with special long handle tongs.
 PATTERN
A pattern is a replica of the object to be cast, used to prepare the cavity into which molten
material will be poured during the casting process.
Patterns used in sand casting may be made of wood, metal, plastics or other materials.
Patterns are made to exacting standards of construction, so that they can last for a reasonable
length of time, according to the quality grade of the pattern being built, and so that they will
repeatably provide a dimensionally acceptable casting.
Fig 13 : PATTERN

38
 MOULD
Mould is hollowed-out block that is filled with a liquid or pliable material like plastic ,glass
,metal or ceramic raw material.
Moulding is the process of manufacturing by shaping liquid or pliable raw material using a
rigid frame called mould.
Fig 14 : MOULD
 GATING SYSTEM
The gating system serves as the path by which molten metal flows into the pattern cavity and
feed the shrinkage which develops during casting solidification.
Fig 15 : GATING SYSTEM

39
 TONGS
Tongs are used for gripping and lifting crucible,of which there are many forms adapted to
their specific use.
Fig 16 : TONGS
 SAND MULLER:
Sand was mixed in the sand muller by adding sodium silicate as a binder.
Fig 17 : SAND MULLER

40
4.2 PREPARING OF ALUMINIUM BRONZE ALLOY (AB1)
Casting process of this alloy started with the melt of pieces of copper and other elements such
as iron, nickel, manganese, zinc and aluminum. During the melting process of alloy elements,
the temperature of molten metal increased to about (1300) °C, but without using any type of
treatment. In addition, the molten metal suffered from severe atmospheric conditions, due to
the absence of protective fluxes. Before pouring the molten metal, a specimen was taken from
the molten metal to check the alloy composition by spectrometer. Then, the molten alloy was
poured into two moulds; sand and metal moulds. The melting process was repeated for the
second charge from the same alloy with sufficient care during melting operation by using
suitable protective layer (Albral 2) to keep the molten metal away from atmospheric
conditions. In addition, steady melting operation was used (no stirring or turbulence). Layer
of charcoal was used on the surface of melt to prevent the oxidation. When the melting
process was finished, a specimen from the molten metal was taken to check the composition
of alloy by spectro-analysis. Preheat the mould to about (100–150) °C before pouring the
metal. The molten metal was poured into a ladle carefully, then, one piece of (Logas 50) was
added to remove the gases out from the molten metal. Two pieces of deoxidizing tubes (E)
were added for reduction of the oxide. Finally, a "non-turbulence casting method" was used to
pour the molten metal into prepared moulds[20].
Fig 18 : HEATING OF CARGE MATERIAL IN PIT FURNACE

41
4.3 PREPARING OF NICKEL - ALUMINIUM BRONZE ALLOY (AB2):
This is the major alloy for this work. The alloy melting is applied as follows: -
After the crucible furnace was discharged from first alloy, it was continued on fire and the
crucible walls show a red colour. The melting process started by charging the pieces of
cathode copper. Then, pieces of iron were added and followed by nickel, manganese, zinc and
aluminum. After the melting operation was finished, molten metal was stirred into the furnace
without any protective layer. The temperature of molten metal increased for about (150) °C
above its pouring temperature (i.e. to about 1350 °C) by increase the furnace flame. The
furnace charge was poured into a prepared sand and metal moulds. In order to explain the
importance of the right procedure of melting for the elements of nickel-aluminum bronze
alloy,
The process was performed as follow : -
The crucible gas furnace was continued on fire. Charging the cathode copper pieces into the
crucible. After melting the copper pieces, a flux of (Albral 2) was used as a protective layer
over the surface of molten metal by 1 % of metal weight. Therefore, the required quantity
from the fluxes during melting operation was about ¾ of all quantity and the reminder was
added before the pouring stage, this quantity is used according to the world specifications[21].
A amount of charcoal was added over the surface of molten metal to prevent the chance of
oxidation. Make an interest to Control on the temperature of the liquid during the melting
operation to prevent the increase in temperature above the required limits. The pieces of iron
were charged under a protective cover carefully. The pieces of nickel and then the pieces of
manganese were added under a protective cover too, followed by zinc pieces and aluminum.
The reminder quantity of (Albral 2) flux was added over the surface of liquid. The alloy
temperature was raised to 1180°C. A specimen from the molten metal was taken to check the
composition of alloy by using a spectro- analysis. Two pieces of (Logas 50) were added and
submerged into the furnace crucible to remove gases from the molten metal.
The molten metal was tilted from the furnace into a ladle to transport it to the moulds. Two
pieces of deoxidizing tubes (E) were placed in the ladle before tilt the molten metal to reduce
the oxides and to increase fluidity to the molten metal[20].
4.4 SLAG REMOVAL:
During the preparation of melt there are lot of impurities present in the molten metal which
reacts with gases or other impurities to form oxide layer when poured in the mould. The oxide
layer doesn’t allow the gas to entrap out of the moulds through vent holes during
solidification or cooling of the mould. Hence resulting into a porous layer inside the casting
which causes the breakage of material during machining or hinders the basic mechanical
properties of the material.

42
Due to the above mentioned disadvantages of the impurities present in the molten metal its
henceforth makes it necessary to remove the impurities before the molten metal is poured in
the mould.
For removing the impurities from the molten metal the various fluxes are added into the
molten metal as mentioned in the earlier section. This fluxes reacts with the impurities to form
a slag which are lighter in weight as compared to the liquid metal and will form a upper most
layer in the crucible and this slag should be removed by pouring the upper most layer out
before pouring it in the mould. The removal of slag is shown in the figure.
Fig 19: REMOVAL OF SLAG
Fig 20: FINAL CASTING

43
Fig 21: MACHINING AFTER CASTING

44
CHAPTER 5: HEAT TREATMENT:
The Al bronze with a nominal composition of Cu-10Al-3Fe was synthesized using liquid
metallurgy route. The process started with the preparation of the charge containing required
quantities of different elements like Cu, Al, and Fe. Cu pieces were charged in a graphite
crucible and melted employing an oil-fired furnace. The melt surface was covered with flux
(Albral) and other alloying elements were added to the melt (maintained at 1170oC )
gradually. Care was taken to add the lower melting elements like Al to add at latter stages of
melting with a view to reduce losses through vaporization. The melt was stirred manually for
some time to facilitate dissolution of the alloying elements.
The solution treatment was carried out at two temperatures (850oC and 900oC ) and duration
in the range of 0.5, 1, 1.5 and 2 hrs respectively. Similarly, ageing was carried out at 300oC,
400oC and 500oC where in the duration of the ageing was maintained at 2 and 3 hrs
respectively. The heat treated samples were subjected to water quenching in order to bring
them to ambient temperature. The behavior of the alloy has been assessed in terms of the
influence of the type, temperature and duration of the heat treatment on the micro structural
and mechanical properties of the samples. Results showed that as cast alloy showed granular
structure consisting of primary α, eutectoid α+ϒ2 and Fe rich phase. Solutionizing led to the
micro structural homogenization by way of the elimination of the dendrite structure and
dissolution of the eutectoid phase and other micro constituents to the form the single phase
structure consisting of β. This was followed by the formation of the β martensite, retained β
and α. Ageing brought about the transformation of the martensite and other micro constituents
into the eutectoid phase. Also, solutionizing at 850oC for 2 hrs led the alloy to attain the
highest hardness in the category of solutionized samples while ageing at 300oC for 2 hrs
offered maximum hardness the aged sample.

45
CHAPTER 6 TESTING AND TEST REPORTS
6.1 Scanning Electron Microscope (SEM)Study:
A scanning electron microscope (SEM) is a type of electron microscope that produces images
of a sample by scanning it with a focused beam of electrons. The electrons interact with
electrons in the sample, producing various signals that can be detected and that contain
information about the sample's surface topography and composition. The electron beam is
generally scanned in a raster scan pattern, and the beam's position is combined with the
detected signal to produce an image. SEM can achieve resolution better than 1 nanometer.
Specimens can be observed in high vacuum, low vacuum and in environmental SEM
specimens can be observed in wet conditions.
Fig 22: Setup of SEM
Principles and Capacities:
The types of signals produced by a SEM include secondary electrons (SE), back-scattered
electrons (BSE), characteristic X-rays, light (cathodoluminescence) (CL), specimen current
and transmitted electrons. Secondary electron detectors are standard equipment in all SEMs,
but it is rare that a single machine would have detectors for all possible signals. The signals
result from interactions of the electron beam with atoms at or near the surface of the sample.
In the most common or standard detection mode, secondary electron imaging or SEI, the SEM
can produce very high-resolution images of a sample surface, revealing details less than 1 nm

46
in size. Due to the very narrow electron beam, SEM micrographs have a large depth of field
yielding a characteristic three-dimensional appearance useful for understanding the surface
structure of a sample. This is exemplified by the micrograph of pollen shown above. A wide
range of magnifications is possible, from about 10 times (about equivalent to that of a
powerful hand-lens) to more than 500,000 times, about 250 times the magnification limit of
the best light microscopes.
Back-scattered electrons (BSE) are beam electrons that are reflected from the sample by
elastic scattering. BSE are often used in analytical SEM along with the spectra made from the
characteristic X-rays, because the intensity of the BSE signal is strongly related to the atomic
number (Z) of the specimen. BSE images can provide information about the distribution of
different elements in the sample. For the same reason, BSE imaging can image colloidal gold
immuno-labels of 5 or 10 nm diameters, which would otherwise be difficult or impossible to
detect in secondary electron images in biological specimens. Characteristic X-rays are emitted
when the electron beam removes an inner shell electron from the sample, causing a higher-
energy electron to fill the shell and release energy. These characteristic X-rays are used to
identify the composition and measure the abundance of elements in the sample.
FIG 23: Test specimens

47
FIG 24: LINE DIAGRAM OF SEM
TESTING RESULT:
Fig 25 : AB1 As Cast

48
Fig 26 : AB1 Heat Treated
Fig 27 : AB1+2% As Cast
Fig 28: AB1+2% Heat Treated
Fig 29: AB2 As Cast

49
Fig 30: AB2 Heat Treated
FIg 31: AB2+2% As Cast
Fig 32 : AB2+2% Heat Treated
OBSERVATION:
From the above structural diagram we can conclude that the structure of cast aluminium i.e.
AB1, AB1+2%, AB2 and AB+2% have dendrite structure and which makes the material
brittle resulting in easy breakage of material and high rate of wear and tear.
On the other hand the heat treated structure diagram of the same composition form Grain
structure improves strength and hardness property of the material and also the conductivity
and magnetic property of the same.

50
6.2 Energy Dispersive X-ray Spectroscopy (EDAX):
Energy-dispersive X-ray spectroscopy (EDS, EDX, or XEDS) is an analytical technique used
for the elemental analysis or chemical characterization of a sample. It relies on the
investigation of an interaction of some source of X-ray excitation and a sample. Its
characterization capabilities are due in large part to the fundamental principle that each
element has a unique atomic structure allowing unique set of peaks on its X-ray spectrum. To
stimulate the emission of characteristic X-rays from a specimen, a highenergy beam of
charged particles such as electrons or protons, or a beam of X-rays, is focused into the sample
being studied. At rest, an atom within the sample contains ground state (or unexcited)
electrons in discrete energy levels or electron shells bound to the nucleus. The incident beam
may excite an electron in an inner shell, ejecting it from the shell while creating an electron
hole where the electron was. An electron from an outer, higher-energy shell then fills the hole,
and the difference in energy between the higherenergy shell and the lower energy shell may
be released in the form of an X-ray. The number and energy of the X-rays emitted from a
specimen can be measured by an energy-dispersive spectrometer. As the energy of the X-rays
is characteristic of the difference in energy between the two shells, and of the atomic structure
of the element from which they were emitted, this allows the elemental composition of the
specimen to be measured.
Fig 33: Information system in SEM

51
Fig 34: Initiation of X-Ray
Equipment
Four primary components of the EDS setup are
1. Excitation source (electron beam or x-ray beam)
2. X-ray detector
3. Pulse processor
4. Analyzer.
Electron beam excitation is used in electron microscopes, scanning electron microscopes
(SEM) and scanning transmission electron microscopes (STEM). X-ray beam excitation is
used in X-ray fluorescence (XRF) spectrometers. A detector is used to convert X-ray energy
into voltage signals; this information is sent to a pulse processor, which measures the signals
and passes them onto an analyzer for data display and analysis. The most common detector
now is Si (Li) detector cooled to cryogenic temperatures with liquid nitrogen; however newer
systems are often equipped with silicon drift detectors (SDD) with Peltier cooling systems.

52
TEST RESULT:
TABLE 5: COMPOSITION for AB1+2%
Fig 35: EDAX study for AB1+2%
Element Wt.%
Al 13.6
Ni -
Fe 4.76
Cu 81.64
Total 100

53
TABLE 6: COMPOSITION for AB1
Fig 36: EDAX study for AB1
Element Wt.%
Al 13.6
Ni -
Fe 4.76
Cu 81.64
Total 100

54
TABLE 7: COMPOSITION for AB2
Fig 37: EDAX study of AB2
Element Wt.%
Al 9.24
Ni -
Fe 4.58
Cu 81.76
Total 100

55
TABLE 8: COMPOSITION for AB2+2%
Fig 38: EDAX study for AB2+2%
Element Wt.%
Al 9.24
Ni -
Fe 4.58
Cu 81.76
Total 100

56
6.3 Hardness testing :
Observations :
Indenter = A steel ball , Diameter - 2.5mm
Load = 10D2
= 10(2.5)2
= 62.5 Kg
TestSpecimens :
Fig 39: TEST SPECIMEN

57
Hardness testing machine :
Fig 40: Brinell Hardness Tester
ObservationTable :
For as cast samples :
TABLE 9: HARDNESS OF CAST SAMPLE
Sr.no Grade Position
Dia. of
indentation
Hardness (HB)
Avg.
Hardness(HB)
1 AB1
Core 0.77 131
129Intermediate 0.77 131
Case 0.78 126
2 AB1+2%
Core 0.70 159
Case 0.70 159
3 AB2
Core 0.70 159
Case 0.70 159
4 AB2+2%
Core 0.73 146
Case 0.63 197

58
For Heat treated samples :
TABLE 10: HARDNESS OF HEAT TREATED SAMPLE
Result & Conclusions :
Sr.no Grades
Avg. Hardness for as cast
samples (HB)
Avg. Hardness for Heat treated
samples (HB)
1 AB1 129 263
2 AB1+2% 159 260
3 AB2 159 151
4 AB2+2% 180 318
TABLE 11: HARDNESS COMPARISION OF CAST SAMPLE AND HEAT
TREATED SAMPLE
From above table, We can conclude that hardness of Heat treated samples are greater than that
of the as cast samples of same composition.
Sr.no Grade Position
Dia. of
indentation
Hardness (HB)
Avg.
Hardness(HB)
1 AB1
Core 0.55 260
Case 0.55 260
2 AB1+2%
Core 0.55 260
Case 0.55 260
3 AB2
Core 0.71 155
Case 0.74 142
4 AB2+2%
Core 0.50 318
Case 0.49 318

59
6.4 Tensile Testing :
Dimensions of test specimens :
inch mm
G- Gage length 2.000 ± 0.005 50.8
D- Diameter 0.500 ± 0.010 12.5
R- Radius of Fillet 3/8 9.525
A-Length of reduced section 2.25 57.15
TABLE 12: DIMENSION OF TEST SPECIMEN
Testspecimens :
Fig 41 : Heat treated samples
Fig 42 : As cast samples

60
Observationtable :
Sr.no Grades
As cast samples Heat treated samples
Tensile
Strength
% Elongation
Tensile
Strength
% Elongation
1 AB1 381 8.4 462 2.22
2 AB1+2% 422 3.78 452 2.6
3 AB2% 315 4.32 359 2.46
4 AB2+2% 457 3.06 211 0.84
TABLE 13: TENSILE STRENGTH OF CAST SAMPLES AND HEAT TREATED
SAMPLES

61
CHAPTER 7 CONCLUSSION :
From the above project we draw the following conclusion
7.1 Reductionin Oxide Formation:
 By varying the compositionof aluminium content in the aluminium
bronze alloy bush.
Pros
The corrosion resistance property of the aluminium bronze component increases which makes
its use feasible for marine applications.
Corns
The enriched aluminium content in the alloy of aluminium bronze increases the thickness of
the oxide layer film which makes the material more porous and brittle, resulting in the
breakage of material during machining
Conclussion:
From the above observations we concluded that the aluminium content should be kept in the
range of 5-14% by weight in aluminium bronze.
 By varying the proportion of alloying agents in the aluminium bronze
alloy.
i) By varying the contentof iron:
Result: The addition of iron up to 1% improves the mechanical properties mainly due to
its effect on grain refinement. However the addition of iron is limited up to 5.5%.Above 1.2%
the tensile strength and hardness are improved but its ductility gets lowered.
ii) By varying the content of nickel:
Result: The addition of nickel to an alloy containing iron has a beneficial effect in
modifying the stable structure.
iii) By varying the content of manganese:

62
Result: The most important effect of manganese is in improving the corrosion resistance of
an aluminium bronze, the addition of magnesium is sufficient up to 6%. The main drawback
is that aluminium bronze with low manganese addition is susceptible to corrosion when the
addition exceeds 11% a fully stable structure is obtained resulting corrosion properties.
 POURING HEIGHT:
Conclusion: The pouring height doesn’t play a much important role in avoiding the
formation of oxides during the pouring of metal in the mould.
 POURING TEMPERATURE:
Conclusion:The temperature should be maintained in the range of 1000 ° C to 1300°C with
the best maintained at 1180°C.
If the temperature is maintained above the mentioned temperature the aluminium bronze alloy
bush which is having an austenite structure is converted into martensite structure which is
brittle in nature and results in breaking of material.
 FLUX ADDITION:
Analysis: When we melt the metal there is a formation of slag which results into the
formation of oxide in the casting.
To avoid it we add the composition of flux into the molten metal which results floating of slag
above molten metal hence it can be easily removed before pouring.
Conclusion: Reduction of oxide formation in aluminium bronze.
 FINDING THE COMPOSITION OF FLUX.
Conclussion: Some of the flux we tried using by mixing various compositions of various
components are:
I. Calcium and sodium fluoride powder
II. Deoxidizing tubes: These tubes are made of copper and contain a powder of
phosphorus and are weight about 25g used as a deoxidizing agent.
III. Logas 50

63
7.2. HEAT TREATMENT:
 Hardness Testing:
Sr.no Grades
Avg. Hardness for as cast
samples (HB)
Avg. Hardness for Heat
treated samples (HB)
1 AB1 129 263
2 AB1+2% 159 260
3 AB2 159 151
4 AB2+2% 180 318
TABLE 14: HARDNESS COMPARISION OF CAST SAMPLE AND HEAT
TREATED SAMPLE
From above table, We can conclude that hardness of Heat treated samples are greater than that
of the as cast samples of same composition.
 Tensile Strength Testing
Sr.no Grades
As cast samples Heat treated samples
Tensile
Strength
% Elongation
Tensile
Strength
% Elongation
1 AB1 381 8.4 462 2.22
2 AB1+2% 422 3.78 452 2.6
3 AB2% 315 4.32 359 2.46
4 AB2+2% 457 3.06 211 0.84
TABLE 15: TENSILE STRENGTH OF CAST SAMPLES AND HEAT TREATED
SAMPLES
From above table, We can conclude that tensile strength of Heat treated samples are greater
than that of the as cast samples of same composition.

64
CHAPTER 8: REFERENCES:
[1] Copper Development Association PUB 80
www.cda.org.uk/enquiry-form.htm.
[2] Copper Development Association PUB 83
www.cda.org.uk/enquiry-form.htm
[3] H. J Meigh, ‘Cast and Wrought Aluminum Bronzes - Properties, Processes and Structure’,
Institute of Materials, London, 2000, 404pp.
[4] P J Macken and A A Smith, ‘The Aluminum Bronzes - Properties and Production
Processes’ CDA Publication No 31, second edition 1966, Copper Development Association,
St Albans, 263pp.
http://www.cda.org.uk/Megab2/corr_rs/pub31/default.htm
[5] Anonymous - “Aluminum Bronze Alloys for Industry” - CDA (UK) Publication No
83,8pp, March 1986
[6] Z. Ahmad and P. Dvami - “The effect of alloying additions on the optimisation of
corrosion resistance and mechanical properties of alpha and beta aluminium bronzes” -Paper
from 6th International Congress on Metallic Corrosion, Books, Sydney, 1975, 28
pages.
[7] J. O. Edwards and D. A. Whittaker - “Aluminum Bronzes containing Manganese, Nickel
and Iron: Chemical Composition, Effect on Structure and Properties” - Trans. A.F.S.,
1961, 69, 862-72.
[8] Aluminum Casting Alloys_english_PV_2012_11_30
[9]Constitution of Binary Alloys. M Hansen and K Anderko, McGraw Hill Book Co, 1957
[10] Eng. & Technology, Vol.25, No.6, 2007 Study on Improvement of Casting Conditions
for Some Aluminum Bronze Alloys
[11] ASTM Standards:
B 208 Practice for Preparing Tension Test Specimens for Copper Alloys for Sand,
Permanent Mold, Centrifugal, and Continuous Castings
[12] A. W. Tracy - “Resistance of Copper Alloys to Atmospheric Corrosion” - A.S.T.M.
Symposium on Atmospheric Exposure Tests on Non-Ferrous Alloys, February, 1946
[13] J. L. Sullivan - “Boundary lubrication and oxidational wear” - J. Physics, D 1999

65
[14] G. W. Lorimer, F. Hasan, J. Iqbal and N. Ridley - “Observation of Microstructure and
Corrosion Behaviour of Some Aluminium Bronzes” - Br. Corros. J. 21, (4), 244-248,1986,
ISSN: 0007-0599
[15] United State, Environmental Protection Agency, "Report on the Corrosion of certain
Alloys",Washington, DC. 20460, July 2001.
[16] P. L. France, "Applied Science in the casting of Metals", 1970
[17] P. Brezina - “Heat treatment of complex aluminum bronzes” - Internat. Met. Reviews,
1982, Vol 27, No 2.
[18] American Foundrymen’s Society; Designation: B 208- 06
Standard Practice for Preparing Tension Test Specimens for Copper Alloy Sand, Permanent
Mold, Centrifugal, and Continuous Castings
[19] For Copper Alloy Casting; FOSECO; 05/2011
[20] Eng & Technology, Vol. 25, No.6, 2007
[21] Burns T. A., Foseco (F.S.) limited, “Foundry man’s Hand book” , Ninth Edi., 1986

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