| 摘要 |
PROBLEM TO BE SOLVED: To improve the problem of collapse resistance as the defect of the conventional martensitic stainless steel and to provide a high strength stainless steel tube excellent in collapse resistance required of a stock for welded steel tube used for structural purpose such as building, and its production. SOLUTION: The stainless steel tube having high strength and high toughness and excellent in collapse resistance has a composition consisting of, by weight, 0.005-0.03% C, 0.05-1.0% Si, 0.05-2.0% Mn, 10-16% Cr, <=2.5% Ni, 0.005-0.03% N, and the balance Fe with inevitable impurities. In this steel sheet, the structure is composed essentially of two phases of ferritic phase and martensitic phase or a single phase of martensite. Further, the length of the grains of inevitably remaining MnS inclusions in a rolling direction is regulated to <=3μm and the ratio between the length of the grains of MnS inclusions in a rolling direction and their length in a direction perpendicular to it is regulated to <=3.0.
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