AISI/SAE Steel Numbering System

CARBON STEELS

10XX

Plain carbon, mn 1.00% max

11XX

Resulfurized free machining

12XX

Resulfurized/rephosphorized free machining

15XX

Plain carbon, mn 1.00-1.65%

MANGANESE STEEL

13XX

MN 1.75%

NICKEL STEELS

23XX

NI 3.50%

25XX

NI 5.00%

NICKEL-CHROMIUM STEELS

31XX

NI 1.25%, CR .65-.80%

32XX

NI 1.75%, CR 1.07%

33XX

NI 3.50%, CR 1.50-1.57%

34XX

NI 3.00%, CR .77%

MOLYBDENUM STEELS

40XX

MO .20-.25%

44XX

MO .40-.52%

CHROMIUM-MOLYBDENUM STEELS

41XX

CR .50-.95%, MO .12-.30%

NICKEL-CHROMIUM-MOLYBDENUM STEELS

43XX

NI 1.82%, Cr .50-.80%, MO .25%

47XX

NI 1.05%, Cr .45%, MO .20-.35%

NICKEL-MOLYBDENUM STEELS

46XX

NI .85-1.82%, MO .20-.25%

48XX

NI 3.50%, MO .25%

CHROMIUM STEELS

50XX

CR .27-.65%

51XX

CR .80-1.05%

50XXX

CR .50%, C 1.00% MIN

51XXX

CR 1.02%, C 1.00% MIN

52XXX

CR 1.45%, C 1.00% MIN

CHROMIUM-VANADIUM STEELS

61XX

CR .60-.95%, V .10-.15%

TUNGSTEN-CHROMIUM STEELS

72XX

W 1.75%, CR .75%

NICKEL-CHROMIUM-MOLYBDENUM STEELS

81XX

NI .30%, Cr .40%, MO .12%

86XX

NI .55%, Cr .50%, MO .20%

87XX

NI .55%, CR .50%, MO .25%

88XX

NI .55%, CR .50%, MO .35%

SILICON-MANGANESE STEELS

92XX

SI 1.40-2.00%, MN .65-.85%, CR 0-.65%

NICKEL-CHROMIUM-MOLYBDENUM STEELS

93XX

NI 3.25%, CR 1.20%, MO .12%

94XX

Ni .45%, Cr .40%, Mo .12%

97XX

NI .55%, CR .20%, MO .20%

98XX

NI 1.00%, CR .80%, MO .25%