ATMOSPHERE CORROSION RESISTING STEEL PLATE HAVING HIGH STRENGTH AND EXCELLENT BENDING FORMABILITY AND METHOD FOR PRODUCTION THEREOF

摘要

An atmosphere corrosion resisting steel plate having high strength and excellent bending formability, characterized in that it has a chemical composition, in mass %: C: 0.05 to 0.15 %, Si: 0.5 % or less, Mn: 0.5 to 2.0 %, P: 0.02 % or less, S: 0.005 % or less, Ni: 0.2 to 2.0 %, Cu: 0.2 to 0.5 %, Cr: 0.2 to 1.0 %; one or more of Ti: 0.03 to 0.2 %, Nb: 0.01 to 0.07 %, V: 0.01 to 0.07 % and B: 0.0005 to 0.0050 %, and balance; Fe and inevitable impurities. A method for producing the above steel plate which comprises heating a steel material having the above composition at a temperature of 1200ringC or higher, completing rolling at a temperature in the range of 850 to 950ringC, and taking up the rolled product at a temperature in the range of 500 to 650ringC. The steel plate secures a ultra high strength of a yield strength of 700 MPa or more, and can endure a bending operation after blasting or the like, and further has good atmosphere corrosion resistance.