COLD ROLLER STEEL SHEET AND GALVANIZED COLD ROLLED STEEL SHEET COMBINING EXCELLENT BAKING HARDENABILITY AND COLD NONAGING PROPERTY AS WELL AND PRODUCTION THEREOF

摘要

PURPOSE:To produce a cold rolled steel sheet combining baking hardenability and cold nonaging properties by forming the structure of steel having a specified chemical compsn. after being annealed into a mixed one. CONSTITUTION:By using the steel constituted of, by weight, 0.0005 to 0.00070% C, 0.001 to 0.8% Si, 0.3 to 4.0% Mn, 0.003 to 0.15% P, 0.0005 to 0.015% S, 0.005 to 0.20% Al and 0.0003 to 0.0060% N, and the balance Fe with inevitable impurities and whose structure is formed into a mixed one of low temp. transformed products and ferrite, this cold rolled steel sheet combining excellent baking hardenability and cold nanaging properties can be produced.