AISI SAE Steel Numbering System

Written by Jerry Ratzlaff. Posted in Metal

Numbering Example

  • \(10xx\)
    • First digit indicates the general category, carbon steels, \(\;1\:\)
    • Second digit indicates the presence of major element %, plain carbon, \(\;0\:\)
    • Last two digit indicates percentage of carbon present in the steel, \(\;xx\;\)
  • \(10Lxx\)
    • First digit indicates the general category, carbon steels, \(\;1\;\)
    • Second digit indicates the presence of major element %, plain carbon, \(\;0\:\)
    • Last two digit indicates percentage of carbon present in the steel, \(\;xx\:\)
    • Letter designation indicates title of the material or specification, lead \(\;L\:\)
  • \(46xx\)
    • First digit indicates the general category, nickel molybdenum steels, \(\;4\:\)
    • Second digit indicates the presence of major element %, nickel, \(\;6\:\)
    • Last two digit indicates percentage of carbon present in the steel, \(\;xx\:\)

Letter Designation

A - Aluminum, B - Brass, C - Copper Alloy, S - Steel, W - Wire, N - Nickel Alloy, L - Lead, M - Magnesium Alloy, M - Magnet or Magnetic, P - Plate Gold, P - Platinum Foil, P - Plating Cadmium, R - Rods Welding, R - Resistance Wire, S - Solder various, S - Steel Bar, S - Steel Alloy sheet and strip, S - Steel Corrosion Resisting, M - Manganese Alloy, S - Steel Castings, B - Bronze, C - Copper, N - Nickel

AISI/SAE Steel Numbering System

NumberingGeneral CategoryMajor Element %
10XX carbon steels Plain carbon, Mn 1.00% max
11XX " Resulfurized free machining
12XX " Resulfurized / rephosphorized free machining
15XX " Plain carbon, Mn 1.00-1.65%
13XX manganese steels Mn 1.75%
23XX nickel steels Ni 3.50%
25XX " Ni 5.00%
31XX nickel chromium steels Ni 1.25%, Cr 0.65-0.80%
32XX " Ni 1.75%, Cr 1.07%
33XX " Ni 3.50%, Cr 1.50-1.57%
34XX " Ni 3.00%, Cr 0.77%
40XX molybdenum steels Mo 0.20-0.25%
44XX " Mo 0.40-0.52%
41XX chromium molybdenum steels Cr 0.50-0.95%, Mo 0.12-0.30%
43XX nickel chromium molybdenum steels Ni 1.82%, Cr 0.50-0.80%, Mo 0.25%
47XX " Ni 1.05%, Cr 0.45%, Mo 0.20-0.35%
46XX nickel molybdenum steels Ni 0.85-1.82%, Mo 0.20-0.25%
48XX " Ni 3.50%, Mo 0.25%
50XX chromium steels Cr 0.27-0.65%
51XX " Cr 0.80-1.05%
50XXX " Cr 0.50%, C 1.00% min
51XXX " Cr 1.02%, C 1.00% min
52XXX " Cr 1.45%, C 1.00% min
61XX chromium vanadium steels Cr 0.60-0.95%, V 0.10-0.15%
72XX tungsten chromium steels W 1.75%, Cr 0.75%
81XX nickel chromium molybdenum steels Ni .30%, Cr 0.40%, Mo 0.12%
86XX " Ni .55%, Cr 0.50%, Mo 0.20%
87XX " Ni .55%, Cr 0.50%, Mo 0.25%
88XX " Ni .55%, Cr 0.50%, Mo 0.35%
92XX silicon manganese steels Si 1.40-2.00%, Mn 0.65-0.85%, Cr 0-0.65%
93XX nickel chromium molybdenum steels Ni 3.25%, Cr 1.20%, Mo 0.12%
94XX " Ni 0.45%, Cr 0.40%, Mo 0.12%
97XX " Ni 0.55%, Cr 0.20%, Mo 0.20%
98XX " Ni 1.00%, Cr 0.80%, Mo 0.25%