Steel for extended automobile crossbeam and mfg, method thereof

This invention relates to a king-sized automobile crossbeam using steal and its manufacturing method, tiny alloy elements of Nb, Ti, V are added in the steal. Their weight percentage is that C 0.07i½0.12, u¼Si 0.15i½0.40u¼ Mn 1.00i½1.50u¼P less than 0.025u¼S less than 0.015u¼Nb 0.020i½0.050u¼V 0.025i½0.050u¼ Ti 0.010i½0.030u¼and tiny Ca, the rest are iron and other tiny impurities. Board butt is continuous cast, rolling and cooling control technique are used in hot rolling, the butt is heated to 1180i½1250 degree centigrade, the temperature is 1020 to 1060 degree centigrade after rough rolling. Then it is finish rolled through blimp, the rolling temperature is maintained at 840 to 880 degree centigrade, the coiled sheet is cooled to 560 to 620 degree centigrade through laminar flow cooling. Because of the multiple unit tiny alloy elements design of the material chemical element, strong strength is got after above process and with good plastic laminar flow, cool formability, so it is specially propitious to king-sized automobile crossbeam making of cladding forming technique.