Tool Steel

Tool Steels are a variety of alloy steels with carbon (generally between 0.5% to 1.5%) that are very well suited to make tools. The major alloying elements they may contain are Tungsten, Molybdenum, Vanadium, Chromium , Cobalt among others, together or in different combination. They offer the required degree of hardness, resistance to abrasion and deformation and the ability to hold cutting edge even at high temperatures. As a result tool steels are suited for their use in the shaping of other materials.

Major Groups of Tool Steels :

1. High speed group

High-speed steel (HSS or HS) is a subset of tool steels, commonly used in tool bits and cutting tools. T-type and M-type tool steels are used for cutting tools when strength and hardness must be retained at high temperatures.

MM1, M7, M10Molybdenum
 M30, M33, M34, M42, M43, M46, M47Molybdenum, Cobalt
 M2, M3, M4Molybdenum, Tungsten
 M6, M15, M35, M36< M41, M44, M45Molybdenum, Tungsten, Cobalt
TT1, T2, T3, T7, T9Tungsten
 T4, T5, T6, T8, T15Tungsten, cobalt

2. Cold-work group

This is a group of three tool steels: oil-hardening, air-hardening, and high carbon-chromium. The steels in the group have high hardenability and wear resistance, with average toughness.

AA2-A10Air hardening, Medium alloys
DD2-D7High carbon, high chromium
OO1 – O7Oil hardening, Low carbon

3. Hot-working group

H-group tool steels were specifically developed to maintain strength and hardness while exposed to prolonged elevated temperatures. H-group tool steels were developed for strength and hardness during prolonged exposure to elevated temperatures.
H1 to H19 are based on a chromium content of 5%
H20 to H39 are based on a tungsten content of 9-18% and a chromium content of 3–4% H40 to H59 are molybdenum based.

HH 10, H11, H12, H13Chromium, Molybdenum
 H14, H16, H19, H23Chromium, Tungsten
 H20, H21, H22, H24, H25, H26Tungsten
 H15, H41, H42, H43Molybdenum

4. Special purpose group / Shock-Resistant

P-type tool steel is short for plastic mold steels. Common steel grades like P20, 420 etc. S-type tool steel is an air or oil hardened Shock resistant toolsteel.

SS1, S3Tungsten
 S2, S4, S5, S6Silicon
PP1- P20, P21Low carbon mold steel