AISI - SAE System of Designating Carbon and Alloy Steels

AISI-SEA System of Designating Carbon and Alloy Steels

This first two digits of a steel's number designate the major alloying elements and the last two or three represent the carbon content in hundredths of a percent.

AISI-SAE Designation*	Types of Steel & Nominal Alloy Content (%)
	Carbon Steels:
10xx	Plain Carbon (Mn 1.00% max.)
11xx	Resulpharized
12xx	Resulpharized and Rephosphorized
15xx	Plain Carbon (Max. Mn range 1.00 to 1.65%)
	Manganese Steels:
13xx	Mn 1.75
	Nickel Steels:
23xx	Ni 3.50
25xx	Ni 5.00
	Nickel-Chromium Steels:
31xx	Ni 1.25; Cr 0.65 and 0.80
32xx	Ni 1.75; Cr 1.07
33xx	Ni 3.50; Cr 1.50 and 1.57
34xx	Ni 3.00; Cr 0.77
	Molybdenum Steels:
40xx	Mo 0.20 and 0.25
44xx	Mo 0.40 and 0.52
	Chromium-Molybdenum Steels:
41xx	Cr 0.50, 0.80 and 0.95; Mo 0.12, 0.25 and 0.30
	Nickel-Chromium-Molybdenum Steels:
43xx	Ni 1.82; Cr 0.50 and 0.80; Mo 0.25
43BVxx	Ni 1.82; Cr 0.50; Mo 0.12 and 0.35; V 0.03 min.
47xx	Ni 1.05; Cr. 0.45; Mo 0.20 and 0.35
81xx	Ni 0.30; Cr 0.40; Mo 0.12
86xx	Ni 0.55; Cr 0.50; Mo 0.20
87xx	Ni 0.55; Cr 0.50; Mo 0.25
88xx	Ni 0.55; Cr 0.50; Mo 0.35
93xx	Ni 3.35; 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
	Nickel-Molybdenum Steels:
46xx	Ni 0.85 and 1.82; Mo 0.20 and 0.25
48xx	Ni 3.50; Mo 0.25
	Chromium Steels:
50xx	Cr 0.27, 0.40, 0.50 and 0.65
51xx	Cr 0.80, 0.87, 0.92, 0.95, 1.00 and 1.05
50xxx	Cr 0.50; C 1.00 min
51xxx	Cr 1.45; C 1.00 min
	Chromium – Vanadium Steels:
61xx	Cr 0.60, 0.80 and 0.95; V 0.10 and 0.15 min.
	Tungsten-Chromium Steels:
72xx	W 1.75; Cr 0.75
	Silicon-Manganese Steels:
92xx	Si 1.40 and 2.00; Ma 0.65, 0.82 and 0.85; Cr 0.00 and 0.65
	High-Strength Low-Alloy Steels:
9xx	Various SAE grades
xxBxx	B denotes boron steels
xxLxx	L denotes leaded steels

*xx in the last two digits of the carbon and low-allow designations indicates that the carbon element (in hundredths of a percent) is to be inserted.