2. JSW STEEL COATED PRODUCTS Ltd. Tarapur
 Total Capacity : 0.75 MTPA.
 Source coils : Vijaynagar and Dolvi.

3.  India’s largest producer and exporter of Coated Products
 The plant has 5 cold rolling mills and five coated strips division (two dual
pots galvanizing cum galvalume lines, two colour coated lines and a 30
MW captive power plant)
 Specialized in Galvanizing , Galvalume and colour coated steels.

4. H.R.
SLITTING
PICKLING
H.R. COILS
COLD
ROLLING
GALVANIZE
GALVALUME
DISPATCH
COLOUR
COATING
PROFILING
CORRUGATED
SHEET

5. WHY
CAL?
Uniformity of
products
Large production
volumes
Less labor
requirement

6. LINE SPECIFICATION:
Type : Continuous annealing line
Furnace Capacity: Grade Ref size(mm) Speed
(mpm)
Capacity(T
PH)
T3 1000*0.2059 374.4 38.8
T2.5 1000*0.1991 398.3 37.5
T2 1000*0.1926 385.2 36.3
T1 1000*0.1801 400 33.9
T4/T5 1000*0.2317 370.7 43.7
DR08/DR10 1000*0.2253 391.8 42.4
Fuel : RLNG
LCV : 8500Kcal/Nm^3

7. MATERIALSPECIFICATION:
Weight 5000 – 25000 kg
Inner diameter 508 mm
Outer diameter 900 – 2000 mm
Strip thickness 0.14 – 0.6 mm
Strip width 650 – 1250 mm
Tensile Strength 700 – 800 MPa

8. ANNEALING FURNACE
 Preheating section
 Radiant tube section
 Soaking Furnace(SF)
 Rapid Cooling Section(RCS)
 Overaging sections(OA)
 Final cooling section(FC)
 Water quenching section(WQ)
Typical annealing cycle in a CAL

9. STEEL GRADE Heating
exit
SF RCS OA FC WQ
Temp( C) Temp( C) Time(s) Exit
Temp
(C)
Enter
Temp
(C)
Exit
Temp
(C)
Time
(s)
Temp
(C)
Temp
(C)
T3 710 710 20 400 400 380 60 <=140 45
T2.5 720 720 20 400 400 380 60 <=140 45
T2 730 730 20 400 400 380 60 <=140 45
T1 750 750 20 400 400 380 60 <=140 45
T4-T5 670 670 20 - - 360 - <=140 45
DR8-DR10 680 680 20 - - 360 - <=140 45
Thermal cycle

10. 0
50
100
150
200
250
300
350
400
450
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7
Linespeed(mpm)
strip thickness(mm)
PRODUCTION CURVE
T3
T2.5
T2
T1
T4/T5
DR08/DR10

11. Effect of annealing(at different temperatures) on Hardness

13. ELECTROLYTIC TINNING LINE

14. PROCESS DESCRIPTION:
• Entry Section : (Entry coil car, Welder, Accumulator, Bridle units,
Deflector rolls, Pinch rolls, Steering system, CPC)
• Process Section : (Cleaning section, Pickling Section, Tin Plating section,
Reflow of tin, Chemical Treatment Section, TFS section)
• Delivery Section (exit) : (Vertical Inspection System ,Exit accumulator,
Exit thickness gauge, Exit snip shear, automatic edge position control, Tension
reel, Exit coil cars)

15. Processes incurred in an ETL :
• Cleaning and Pickling : removing loose particles and rolling oils
 Cleaning/Pickling Process : Electrolytic
 Cleaning/Pickling Current : 18000 A – 32 V
• Tin Plating :
 12 vertical tanks, 9 for electroplating and 3 (for drag and rinse)
 Plating Process : Phenol Sulfonic acid Plate(PSA & Future provision for MSA)
 Plating Current : 153000 A – 32 V with 16 % plating efficiency
Electrolyte : Phenol
Sulphonic Acid (PSA)

16. • Reflow :
 Reflowing involves reheating the tin above its Melting Point(231C/450F)
 reduces the internal stresses
 improves the bond between the tin plating and the base material.
 provides good thickness uniformity and a glossy surface finish.
 Parts treated with reflowed tin exhibit excellent corrosion resistance.
 increase its solderability.
• Quench Tank : for lowering strip temperature to 45oC
Temp in/out (oC) 50/275
Power in strip (kW) 1000

17. • Chemical Treatment :
 to stabilize the tin oxide layer (formed during induction reflow in the presence
of air) by electrolytic treatment with sodium dichromate.
 Temperature : 44-58 oC
• Oiling :
The clean, dried strip passes through an electrostatic oiler in which the
required amount of lubricant is deposited.
• TIN FREE STEEL (TFS) Section :
 apply coatings of metallic chrome and chrome hydroxide on the steel strip
surface.

18. • Tin Free Steel :
Tin free steel (TFS) is composed of four layers, including steel base,
metallic chromium layer, chromium oxide layer and oil film

19. INCOMING Coil Characteristics :
Material Medium and low carbon steel , cold rolled and
tempered (EN 10202:2001)
Steel Grades • SR:T1 –T5
DR: DR480, DR8, DR9, DR10
Yield Strength • SR: 230 – 550 N/mm2
DR: 350 – 700 N/mm2
Coil weight 25 ton (max)
I.D 508mm
O.D 914-1950 mm
Surface iron and oil 75-150 mg/m2 per side

20. OUTGOING Material Characteristics :
Material Tin Plate andTFS
Coil weight 25 ton(max.)
I.D 420/508mm
O.D 914 - 1950 mm
CoatingType Tin Plate(PSA & Future provision for MSA) and
TFS(2 steps)
Coating weight Tinplate
0.56 to 16.8 g/m2 per side
TFS
50 to 140 mg/m2 per side(Chromium)
7 to 35mg/m2 per side (Chromium in Oxide)
ChemicalTreatment • Sodium Dichromate
2 – 10 mg/m2 ,Cr each side (for 311 type)
1 – 3 mg/m2 ,Cr each side (for 300 type)

21. Entry section speed 500 m/min
Process section speed 400 m/min.
Exit section speed 500 m/min
Acceleration/Deceleration rate 45 m/min/s
Technical Data :

22. An alternative approach :
 MSA as an electrolyte (instead of PSA) :
The MSA bath is a plating bath which is composed mainly of methane
sulfonic acid (CH3SO3H) and Sn2, and has the following features:
• . Sludge generation is small
• Because the main components of the sludge are Sn(OH)4 and SnO2,
recycling is easy.
• The proper electrolysis current density (10– 55A/dm2) is wide

23. Pitfalls of using an MSA bath :
• The MSA bath is strongly corrosive (pH 1).
• The unit cost of the electrolyte is extremely high in comparison with the
halogen bath.

24. Himanshu Sankhe