Category

Description

Materials Designation

A

Air Hardening

A2, A3, A4, A5, A6

D

Oil or Air Hardening
(High Carbon, High Chromium)

D1, D2, D3, D4, D5, & D7

H

Hot Working
(Chromium, Tungsten, Molybdenum)

H10, H11, H12, H13, H14, H16, H19, H20,
H21, H22, H23, H24, H25, H26, H27, H41, H42, & H43

L

Special Purpose
(Low Alloy)

L2, L3, L6, & L7

M

High Speed (Molybdenum)

M1, M2, M3(I), M3(II), M4, M6, M7, M10, M15, M30, M33, M34, M36, M41, M42, M43, M44, M46, M47, & M50

O

Oil Hardening

O1, O2, O6, & O7

P

Mold Making

P2, P3, P4, P5, P6, P20, & P21

S

Shock Resisting

S1, S2, S5, & S7

T

High Speed (Tungsten)

T1, T2, T3, T4, T5, T6, T7, T8, T9, T15

W

Water Hardening

W1, W2, & W5