Q.: While inspecting reinforcing bars that were to be used on a project, I found several bundles designated N for type of steel. I know that the designations S, I, A and W indicate billet, rail, axle and low-alloy steels, respectively. But I can't find any ASTM reference to Type N. What kind of steel is it?
A.: Anthony Felder of the Concrete Reinforcing Steel Institute says that the bars are made of billet steel. The N stands for new billet steel. Until 1984, ASTM A 615, Standard Specification for Deformed and Plain Billet-Steel Bars for Concrete Reinforcement, included two types of billet steel, N and S. Type S steel met more stringent supplementary requirements, which were optional. In 1984, these supplementary requirements were moved into the main body of the specification, the Type S designation was kept for consistency, and the Type N designation was dropped.
You can conclude, therefore, that the steel you inspected was produced in 1984 at the latest, and it may not meet the current ASTM A 615 requirements.