STEEL SHEET EXCELLENT IN EMBRITTLEMENT RESISTANCE TO BRAZING FILLER METAL AND PRODUCTION OF THE COLD ROLLED STEEL SHEET

摘要

PURPOSE: To produce a cold rolled steel sheet excellent in embrittlement resistance to brazing filler metal, suitable for use in the case where a steel sheet after working is brought into contact with molten metal, e.g. the case where brazing is done after working such as deep drawing. ;CONSTITUTION: This steel sheet has a composition containing, by weight, ≤0.004% C, 0.0002-0.0015% B, 0.002-0.02% Cu, and further 0.005-0.08% Ti and/or 0.005-0.05% Nb and satisfying B×Cu≤2×10⁵. A steel having this composition is cast continuously and finish rolling is finished in a temp. range not lower than the Ar₃ point, and a hot rolled steel strip coiled at 600-700°C is descaled and cold-rolled at 65-85% draft, and the resulting steel sheet is continuously annealced at 780-880$0C. At this time, the dew point in an annealing atmosphere is regulated to ≤-20°C. By this method, the cold rolled steel sheet can be produced.;COPYRIGHT: (C)1996,JPO