basics of Tool steel

Tool steel

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 – 9 th 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