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AISI - SAE DESIGNATION SYSTEM FOR CARBON AND ALLOY STEELS
DIGITS TYPE OF STEEL NOMINAL % OF ALLOY CONTENT
10XX Plain Carbon 1.00% Mn, Max
11XX Resulfurized
12XX Resulfurized and Rephosphorized
13XX Manganese Steel 1.75 Mn
15XX Plain Carbon Steel 1.00 - 1.65 Mn
23XX Nickel Steel 3.50 Ni
25XX Nickel Steel 5.00 Ni
31XX Nickel-Chromium Steel 1.25 Ni, 0.65 and 0.80 Cr
32XX Nickel-Chromium Steel 1.75 Ni, 1.07 Cr
33XX Nickel-Chromium Steel 3.50 Ni, 1.50 and 1.57 Cr
34XX Nickel-Chromium Steel 3.00 Ni, 0.77 Cr
40XX Molybdenum Steel 0.20 and 0.25 Mo
41XX Chromium-Molybdenum Steel 0.50, 0.80, and 0.95 Cr; 0.12, 0.20, 0.25 and 0.30 Mo
43XX Nickel-Chromium-Molybdenum Steel 1.82 Ni, 0.50 and 0.80 Cr, 0.25 Mo
43BVXX Nickel-Chromium-Molybdenum Steel 1.82 Ni, 0.50 Cr, 0.12 and 0.25 Mo, 0.03V Min
44XX Molybdenum Steel 0.40 and 0.52 Mo
46XX Nickel-Molybdenum Steel 0.85 and 1.82 Ni, 0.20 and 0.25 Mo
47XX Nickel-Chromium-Molybdenum Steel 1.05 Ni, 0.45 Cr, 0.20 and 0.35 Mo
48XX Nickel-Molybdenum Steel 3.50 Ni, 0.25 Mo
50XX Chromium Steel 0.27, 0.40, 0.50 and 0.65 Cr
51XX Chromium Steel 0.80, 0.87, 0.92, 0.95, 1.00 and 1.05 Cr
50XXX Chromium Steel 0.50 Cr, 1.00 C Min
51XXX Chromium Steel 1.02 Cr, 1.00 C Min
52XXX Chromium Steel 1.45 Cr, 1.00 C Min
61XX Chromium-Vanadium Steel 0.60, 0.80 and 0.95 Cr; 0.10 and 0.15 Min V
72XX Tungsten-Chromium Steel 1.75 W, 0.75 Cr
81XX Nickel-Chromium-Molybdenum Steel 0.30 Ni, 0.40 Cr, 0.12 Mo
86XX Nickel-Chromium-Molybdenum Steel 0.55 Ni, 0.50 Cr, 0.20 Mo
87XX Nickel-Chromium-Molybdenum Steel 0.55, 0.50 Cr, 0.25 Mo
88XX Nickel-Chromium-Molybdenum Steel 0.55 Ni, 0.50 Cr, 0.35 Mo
92XX Silicon-Manganese Steel 1.40 and 2.00 Si; 0.65, 0.82, and 0.85 Mn; 0.00 and 0.65 Cr
93XX Nickel-Chromium-Molybdenum Steel 3.25 Ni, 1.20 Cr, 0.12 Mo
94XX Nickel-Chromium-Molybdenum Steel 0.45 Ni, 0.40 Cr, 0.12 Mo
97XX Nickel-Chromium-Molybdenum Steel 0.55 Ni, 0.20 Cr, 0.20 Mo
98XX Nickel-Chromium-Molybdenum Steel 1.00 Ni, 0.80 Cr, 0.25 Mo
Two of the most widely used specification and designation systems for carbon and alloy steels were developed by the American Iron
and Steel Institute (AISI) and the Society of Automotive Engineers (SAE).
Although these are two different systems, they are nearly identical. The systems are set up to show the chemical composition of the
steel.
The first two digits show the major alloying elements; the last two digits indicate the nominal carbon content in 1/100th’s of a percent.
The definition of carbon steel is a steel that contains less than 1.65% Mn, 0.60% Si, and 0.60% Cu. Carbon Steels are broken down
into four groups, based on carbon content:
High Carbon Steels .60 to 1.70 % C
Medium Carbon Steels .30 to .59 % C
Mild Carbon Steels .15 to .29 % C
Low Carbon Steels up to .15 % C
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