This document discusses the basics of tool steels, including their types and applications. It outlines the four key factors for successful tool steel application: tool design, fabrication accuracy, steel selection, and heat treatment. It then describes various types of tool steel grouped by their intended application, such as high speed steels, hot work steels, cold work steels, shock resisting steels, and mold steels. For each group, it provides details on composition, hardness, uses, and heat treatment considerations.

1. BASICS OF TOOL STEELS
Types and Applications

2. TOOL STEEL PERFORMANCE
The Four Factors
Required for Successful Application
• Tool Design
• Accuracy of Fabrication
• Tool Steel Selection
• Correct Heat Treatment

3. TYPES OF TOOL STEEL
• High Speed Steels
– Group M – Molybdenum
– Group T – Tungsten
• Hot Work Steels
– Chromium
– Tungsten
– Molybdenum
• Cold Work Steels
– Air Hardening
– High Carbon, High Chromium
– Oil Hardening

4. TYPES OF TOOL STEEL
• Shock Resisting Steels
• Low Alloy Special Purpose Steels
• Mold Steels
• Water Hardening Steels

5. GROUP M HIGH SPEED
• Used for High Speed Cutting Tools –
Account for Over 95% Of Total Useage
• Contain Mo, W, Cr, V, Co
• Superior Toughness
• Maximum Hardness Ranges from HRC 65
to HRC 70 – Depending Upon Grade
• Type M-2 Has Best Resistance to
Softening at Elevated Temperatures

6. GROUP T HIGH SPEED
• First Developed in Early 1900’s
• Contain W, Cr, V
• Extremely Deep Hardening
• High Red Hardness (Similar to Group M)
• High Wear Resistance
• More Expensive Than Group M Steels

7. CHROMIUM HOT WORK STEELS
• H10 – H19
• Medium Carbon Content
• High Toughness @ HRC 40-55
• Deep Hardening – up to 6” in Air
• Low Distortion During Hardening
• Used for Tooling at Elevated
Temperatures – Same as W, Mo Grades

8. TUNGSTEN HOT WORK STEELS
• H21 – H26
• Extra Resistant to Softening
• More Prone to Brittleness
• Working Hardness Range is HRC 45-55
• Quench in Oil or Salt to Minimize Scaling

9. MOLYBDENUM HOT WORK
STEEL
H42 is Only Grade in Current Use
Low Carbon Content
Greater Toughness Than Tungsten Grades
Lower Cost

10. AIR HARDENING COLD WORK
STEELS
• Air Harden Up To 4” Thick Sections
• Minimum Distortion
• Least Tendency to Crack During
Hardening
• Used for Shear Knives, Punches,
Blanking/Trimming Dies, Forming Dies,
Coining Dies

11. HIGH C, HIGH CR COLD WORK
STEELS
• Group D Steels – Carbon From
1.50/2.35%
• High Softening and Wear Resistance
• Susceptible to Edge Brittleness
• Dies For Long Runs – Blanking, Forming,
Thread Rolling, Deep Drawing, Shear and
Slitter Knives

12. OIL HARDENING COLD WORK
STEELS
• Group O Steels
• High Carbon Contents – 0.85-1.55%
• Quench in Oil
• High Wear Resistance
• Hardness Ranges From HRC 56-62
• Used for Punches and Dies, Machinery
Components, Gages

13. SHOCK RESISTING STEELS
• Group S - Medium Carbon – 0.40-0.55%
• High Strength, Toughness
• Good Wear Resistance at Low /Medium
Temperatures
• Used for Chisels, Rivet Sets, Driver Bits
• Also Considered for Some Structural
Applications

14. LOW ALLOY SPECIAL PURPOSE
• Group L – Types L2 and L6 Currently
Available
• Usually Oil Quenched
• Can Be Water Quenched
• L2 – Hardness – HRC 57
• L6 – Hardness – HRC 64
• Used for Machine Parts – Arbors, Cams,
Chucks, Collets

15. MOLD STEELS
• Group P – Low Carbon Steels
• P2 – P6 Are Carburizing Grades
• Can Achieve Surface Hardness of HRC 58
• P20, P21 – Hardened to HRC 30-36
• Used for Low Temperature Die Casting
Dies and Plastic Mold Dies
• Electric Furnace Melted, Vacuum
Degassed, Deoxidized

16. WATER HARDENING STEELS
• Group W – Medium to High Carbon
• Shallow Hardening
• Hard Case Over Tough Core
• Used for Cold Heading, Striking,
Embossing, Woodworking, Taps,
Reamers, Machine Tool Components

17. HEAT TREATMENTS
• Most Tool Steels Require Heat Treatment
After Fabrication
• Generally Respond Best To Slow Heating
Rates – Promotes Uniformity
• Groups M, T, and H Are Exceptions
• Quench Media Need To Be Clean and At
Uniform Temperature
• Consult Steel Suppliers For Specific
Recommendations

18. RESOURCES
• ASM Metals Handbook – 9th Ed., Vol. 3
• Tool Steels – A.I.S.I., 1978
• Tool Steels – Roberts & Cary; ASM, 1980
• Heat Treatment of Ferrous Alloys –
Brooks; McGraw-Hill 1979
• Distortion In Tool Steels – Lement; ASM
1959