Technical reference
Reading designations
How steel names are built in the SAE, EN, BS 970, IS and JIS systems, decoded part by part.
SAE / AISI numbers
A four-digit SAE/AISI number such as 1045 or 4140 names a carbon or alloy steel by its chemistry: the first two digits identify the steel family and the last two give the nominal carbon content in hundredths of a percent.
Read the reference →EN 10027 names and numbers
European steels carry two identifiers under EN 10027: a steel name (Part 1) such as S235JR, C45 or 42CrMo4 that describes the steel's use or chemistry, and a material number (Part 2) such as 1.0503 or 1.7225.
Read the reference →BS 970 and the EN series
BS 970 names steels with a six-character code such as 080M40, in which the first three digits give the steel type, the letter says how the steel is specified and the last two digits give the carbon content.
Read the reference →IS 1570 and Indian designations
Indian steel names follow the letter-symbol code in IS 1762 (Part 1), which the IS 1570 schedules use: 45C8 means about 0.45% carbon, C for carbon steel and about 0.8% manganese, while alloy names such as 40Cr4Mo3 list each element with a multiplied content figure.
Read the reference →JIS steel designations
Japanese JIS steel symbols start with S for steel and add letters for the steel family or its use, but the number means different things in different standards.
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