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%

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