Patent ID: 6129999
Filing Date: 2000-10-10
Classification: B23K,Y10T

Abstract:
A welded high-strength steel structure having an excellent corrosion resistance in a wet carbon dioxide environment with a low H.sub.2 S concentration, a Vickers hardness of not greater than 350 and a welded joint tensile strength of not less than 620 MPa, said steel structure comprising:a) a martensitic stainless steel as a base metal whose microstructure is of the martensitic phase or tempered martensitic phase and whose chemical composition includes, on a weight basis:C: 0.001% to 0.05%Cr: 9% to 14%Si: not greater than 1%Mn: not greater than 5%Ni: 4.5% to 7%sol. Al: 0.001% to 0.2%Mo: 0% to 4%Cu: 0% to 3%W: 0% to 5%Ti: 0% to 0.2%Nb: 0% to 0.2%Zr: 0% to 0.2%Ca: 0% to 0.01%B: 0% to 0.01%and the balance of Fe and unavoidable impurities asP: not greater than 0.03% andS: not greater than 0.01%; andb) an austenitic-ferritic stainless steel as a weld metal whose micrtostructure is a duplex structure composed of the austenitic phase and 35% to 75% by volume of the ferritic phase and whose chemical composition includes, on a weight basis:Cr: 22% to 27%Ni: 7% to 11%Mo: 1.5% to 5%Si: not greater than 1%Mn: not greater than 2%sol. Al: 0.005% to 0.1%N: 0.22% to 0.4%Cu: 0.0% to 2.0%W: 0.0% to 3.5%Ti: 0.0% to 0.15%Nb: 0.0% to 0.15%Zr: 0.0% to 0.15%Ca: 0.0% to 0.01%B: 0.0% to 0.01%and the balance of Fe and unavoidable impurities includingC: not greater than 0.03%p: not greater than 0.02% andS: not greater than 0.01%.