Process for production of steel tubes from hot rolled strip steel, especially by high internal pressure forming, useful in the production of tubes with longitudinal weld seams for the automobile industry

摘要

A process for production of steel tubes from hot rolled strip steel of starting tensile strength Rm greater than 600 N/square mm, proof stress Rp 0.2 greater than 500 N/square mm, and extension factor A5 greater than 24% containing the alloy constituents:C, Si, Mn,P, S, Al, Nb, and iron and melting determined residual impurities, where the strip steel is formed to a tube, welded, and finally subjected to normalizing cooling is new. A process for production of steel tubes from hot rolled strip steel of starting tensile strength Rm greater than 600 N/square mm, proof stress Rp 0.2 greater than 500 N/square mm, and extension factor A5 greater than 24% containing the alloy constituents (%):C (0.02-0.07), Si 0.12 max, Mn (1.30-1.60), P (0.020 max), S 0.005), Al 0.020-0.060, Nb (0.070-0.120), iron and melting determined residual impurities, where the strip steel is formed to a tube, welded, and finally subjected to normalizing cooling.