| 摘要 |
PROBLEM TO BE SOLVED: To provide a martensitic stainless steel excellent in corrosion resistance after fatigue and usable as a coiled tubing for a pipeline for the production/transportation of petroleum/natural gas. SOLUTION: The stainless steel has a composition containing C, Si, Mn, P, S, Cr, NI, Al and N, also containing, if necessary, Nb, V, Ti and Zr, and further containing Ca, Mg, La and Ce, and further, the ratio of martensite in the tempered structure is regulated to >=95%. By subjecting a steel pipe manufactured using this martensitic stainless steel to repeated fatigue in three or more cycles, fatigue resistance and corrosion resistance can be improved.
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