carbon steel

carbon steel (countable and uncountable, plural carbon steels)

1. Any of a range of alloys of iron and carbon whose properties depend on the proportion of carbon.
   • 1951 March, “British Railways Standard "Britannia" Class 4-6-2 Locomotives”, in Railway Magazine, page 186:

     All springs for the engine and tender are of the laminated type with plates of carbon steel, which are secured in the spring buckles by a vertical centre rivet.

• mild steel

• Eastern Bloc