Ferritic stainless steel excellent in corrosion resistance and strength of weld zone and tig welded structure

摘要

Disclosed are ferrite stainless steel compositions and welded structures that exhibit high weld-zone strength and weld-zone corrosion resistance, particularly with respect to crevice corrosion, even if an argon-gas shield is not used during TIG welding. In a corrosive environment, the corrosion resistance of a ferrite stainless steel containing prescribed amounts of constituents can be increased by using constituent mass percentages that satisfy formula 1. In a more corrosive environment, a welded structure that resists crevice corrosion can be produced by not only having the relationship between the constituents of the steel satisfy formula 1, but also having the relationship between the thickness of the steel sheet and the length of the weld bead exposed on the back surface satisfy formula 2. Weld strength can also be improved by having the amounts of niobium and vanadium satisfy formula 3, resulting in a welded structure exhibiting high weld strength. Formula 1: Si + 2.5Al + 3Ti ≤ 1.50 Formula 2: 0 < Wb/2t ≤ 1.50 (t being the thickness of the material being welded and Wb being the length of the weld bead exposed on the back surface) Formula 3: Nb×V ≥ 0.01