Germany has a unique way of expressing steel grades. They are represented by two numbers, followed by a letter showing the type of steel. The first number is the material group and the second is the sub-group which represents the strength class.
Here are the individual groups and their representing letters:
Group 1 - Non-Alloyed Structural Steel:
St ≈ Structural Steel
Ust ≈ Unalloyed Structural Steel
Group 2 - Quenched and Tempered Steels:
QT ≈ Quenched and Tempered Structural Steel
Group 3 - Condition-hardened Steels:
CH ≈ Condition-hardened Structural Steel
Group 4 - Non-Quenched and Tempered Structural Steel:
NQT ≈ Non-Quenched and Tempered Structural Steel
Group 5 - Alloyed Construction Steel:
AS ≈ Alloyed Structural Steel
Group 6 - Tool Steels:
TS ≈ Tool Steel
Group 7 - High Speed Steels:
HS ≈ High Speed Steel
Group 8 - Special Steels for Cold Work:
SC ≈ Special Steel for Cold Work
Group 9 - Special Steels for Hot Work:
SH ≈ Special Steel for Hot Work
Group 10 - Low Alloyed Steel:
LA ≈ Low Alloyed Steel
Group 11 - Ferritic Structural Steel:
FE ≈ Ferritic Structural Steel
Group 12 - Martensitic Structural Steel:
MA ≈ Martensitic Structural Steel
Group 13 - Austenitic Structural Steel:
Au ≈ Austenitic Structural Steel
Group 14 - Ferritic Stainless Steel:
FS ≈ Ferritic Stainless Steel
Group 15 - Martensitic Stainless Steel:
MS ≈ Martensitic Stainless Steel
Group 16 - Austenitic Stainless Steel:
AS ≈ Austenitic Stainless Steel
Group 17 - Extra-Low Carbon Ferritic Steel:
EC ≈ Extra-Low Carbon Ferritic Steel
Group 18 - Creep Resistant Steel:
CR ≈ Creep Resistant Steel
Sometimes the strength class is not indicated, and when it’s not you may use a heuristic method to guess what it might be. In general, if the first number is in the range of 1-12 then the second number is probably 0 or 8.
For a more precise number you can look up the material in the DIN 17006 EN 10025-4 catalog, which lists all German steel grades for construction steel and tools, along with their specific strength classes.
To sum up, the way German steel grades are expressed is a unique system that requires a little bit of extra knowledge to understand. With a bit of research, you can figure out which steel grade is which, and use it in your own projects.
