AISI/SAE Steel and Alloys - Designation System
The AISI/SAE carbon steel and alloys naming conventions.
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AISI/SAE steel numbers are indicated below.
- AISI - American Iron and Steel Institute
- SAE - Society of Automotive Engineers
Alloy steels and carbon steels can be designated with specific grades by a four-digit AISI/SAE numerical index system. The system is based on the chemical compositions of the steels and alloys.
Example AISI/SAE No. 1020
- the first digit indicates that this is plain carbon steel.
- the second digit indicates there are no alloying elements
- the last two digits indicates that the steel contains approximately 0.20 percent carbon
Example AISI/SAE No. 4340
- the first two digits indicates a Nickel-Chromium-Molybdenum alloy steel
- the last two digits indicates carbon content roughly 0.4 percent
| AISI/SAE Designation | Steel/Alloy | Chemical Composition |
|---|---|---|
| 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 steel | 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% |
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