| 摘要 |
PURPOSE:To improve the corrosion resistance in the weld zone of a two-phase stainless steel as high as that of the base material by subjecting the weld zone to adequate cold working then to a soln. heat treatment in a specific temp. range. CONSTITUTION:The weld zone of a two-phase stainless steel is subjected to cold working such as cold rolling, spinning, pressing, pulling, compressing or the like at >=4% reduction ratio then to a heat treatment at 1,000-1,200 deg.C heating temp. to form a solid solution. The precipitate in the weld zone is solutionized by such treatment and at the same time the formation of the finer crystal grains in the weld zone is accelerated and the distributing amt. of the alloy components between the formed ferrite and austenite is made equiv. to that of the base material; moreover the corrosion resistance is improved as much as that of the base material. If the cold reduction ratio is <4% in the above-mentioned method, the effect of forming the finer grains in the stage of the heat treatment is not enough and if the temp. of the heat treatment to form a solid solution is <1,000 deg.C, the formation of solid solution of nitride is not possible. If said temp. exceeds 1,200 deg.C, the two-phase structure of austenite and ferrite is hardly obtainable. |
