Tool Steels

Tool steel is a type of high-quality carbon and alloy steel that is specifically designed for the production of tools and dies used in manufacturing processes. These materials are heat-treated to achieve a balance of toughness, wear resistance, and hardness. They are commonly used to produce cutting and forming tools, as well as molds and dies for the production of plastic, metal, and other materials.

Tool steels are generally divided into five groups¹:

Water-hardening tool steels
Cold-working tool steels
Shock-resisting tool steels
High speed steels
Hot working tool steels

Tool steels are generally quenched in one of three ways. Water-hardening tool steels are the most commonly used and are quenched in water to achieve a hard and wear-resistant surface. Oil-hardening tool steels are quenched in oil to achieve greater toughness and better resistance to shock loading. Air-hardening tool steels are the most expensive and are quenched in air to achieve the highest level of wear resistance, toughness, and hardness.

Tool Steels

References

ASTM A600 Standard Specification for Tool Steel High Speed
ASTM A681 Standard Specification for Tool Steels Alloy
ASTM A686 Standard Specification for Tool Steel, Carbon
ASTM A597-14 Standard Specification for Cast Tool Steel

Note: ASTM classifies tool steels as 1) Carbon Tool Steel, 2) Alloy Tool Steel, or 3) Cast Tool Steels ↩︎

A Series Cold Work Tool Steels

Types A2 through A10 are able to harden in an air quench. Types A8 and A9 are low-carbon, and have increased toughness but decreased hardness compared to the other grades. Type A7 has high carbon and vanadium content, and exhibits exceptional hardness and wear resistance, but with poor toughness. See ASTM A681

H Series Hot Work Tool Steels

Types H10 to H19 exhibit controlled chromium content alongside various other alloying elements. The initial four types, which include molybdenum, demonstrate outstanding toughness and a high capacity for hardening. As a result, they are commonly employed in cold work applications that demand toughness even at relatively elevated levels of hardness. Types H21 to H26 feature...

W Series Carbon Tool Steels

Often referred to as water hardening tool steels or carbon tool steels, these steels must be quenched rapidly, and generally result is a hard exterior with a softer interior. These tool steels are generally lower cost than alloy tool steels. See ASTM A686

T & M Series High Speed Tool Steels

High-speed steel is named for its resistance to softening at elevated temperatures, which enables it to cut through materials at higher speeds compared to plain carbon steels. It is composed of iron along with specific elements such as tungsten (T series) or molybdenum (M series), along with carbon, chromium, vanadium, and occasionally tungsten or cobalt....