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basics of Tool steel
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.
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Overview of tool steels, their types and applications.
Essential factors: Tool design, fabrication accuracy, steel selection, and heat treatment.
Various tool steels include high speed, hot work, cold work, shock resisting, low alloy, mold, and water hardening steels.
High Speed Steel Group M: Used widely, superior toughness, and specific hardness range.
High Speed Steel Group T: Early 1900s origin, notable for deep hardening and wear resistance.
Characteristics of chromium hot work steels, suitable for tooling at high temperatures.
Properties of tungsten hot work steels, prone to brittleness but resistant to softening.
Molybdenum hot work steel (H42): Low carbon, greater toughness, cost-effective.
Air hardening properties: minimal distortion and use in shear knives and dies.
Group D cold work steels: high wear resistance, used for long-run dies.
Group O cold work steels: high carbon, high wear resistance, used for dies.
Group S steels: medium carbon, high toughness, used for chisels and structural applications.
Group L steels: oil quenched, with specific hardness, used for machine parts.
Group P mold steels: low carbon, used for die casting and plastic molds.
Group W water hardening steels: used in various applications like cold heading.
Heat treatment for tool steels: effects of heating rates and quench media.
References for further reading on tool steels and heat treatment.
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basics of Tool steel
- 1. BASICS OF TOOLSTEELS Types and Applications
- 2. TOOL STEEL PERFORMANCE TheFour Factors Required for Successful Application • Tool Design • Accuracy of Fabrication • Tool Steel Selection • Correct Heat Treatment
- 3. TYPES OF TOOLSTEEL • 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 TOOLSTEEL • Shock Resisting Steels • Low Alloy Special Purpose Steels • Mold Steels • Water Hardening Steels
- 5. GROUP M HIGHSPEED • 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 HIGHSPEED • 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 WORKSTEELS • 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 WORKSTEELS • 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 H42is Only Grade in Current Use Low Carbon Content Greater Toughness Than Tungsten Grades Lower Cost
- 10. AIR HARDENING COLDWORK 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, HIGHCR 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 COLDWORK 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 SPECIALPURPOSE • 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 • GroupP – 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 • MostTool 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 MetalsHandbook – 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