| 摘要 |
PURPOSE: To impart the conditions in the blooming and the subsequent heating of a square bloom for producing a seamless steel pipe of a martensitic stainless steel used for an oil well pipe. CONSTITUTION: The continuously cast slab of a martensitic stainless steel contg., by weight, 0.15 to 0.22% C, 12 to 14% Cr and <=0.0025% S is subjected to blooming at >=2 of edging ratio in the temp. range of <=1100 to >=900 deg.C and is rolled into a square bloom, and after the blooming, it is heated to 1100 to 1200 deg.C for >=2hr, by which Cr solidified and segregated in the central segragating part of the bloom is diffused, and the remainingδferrite is almost completely eliminated. Thus, the produced square bloom of the martensitic stainless steel is used, by which the generation of defects in the internal surface can be avoided.
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