PRODUCTION OF SHEET EXCELLENT IN CHARACTERISTIC IN WELD ZONE

摘要

PURPOSE:To produce a sheet excellent in characteristics in weld zone by adding specific amounts of B to a low carbon steel having a specific composition consisting of C, Si, Mn, Al, N, and Fe, subjecting the above steel to hot rolling and cold rolling, and further carrying out batch annealing. CONSTITUTION:B is added by 0.005-0.0030% B to a low carbon steel having a composition consisting of 0.02-0.08% C, =0.03% Si, =0.40% Mn, 0.005-0.070% Al, 0.0010-0.0100% N, and the balance Fe with inevitable impurities. This steel is hot-rolled and cold-rolled. Then, the resulting sheet is further subjected to batch annealing. By this method, the hardening of a welding nugget in a weld zone by a spot welding method, etc., can be attained and also the stabilization of fracture strength and the improvement of fracture form in the weld zone can be attained, by which the sheet excellent in characteristics in weld zone can be obtained.