| 摘要 |
The present invention provides a martensitic stainless steel seamless pipe, having no inner surface defect and suppressing a delayed fracture generation in the impact-worked portions, and a method for manufacturing such a seamless steel pipe. A martensitic stainless steel seamless pipe, characterized by consisting of C: 0.15 to 0.22%, Si: 0.1 to 1.0%, Mn: 0.10 to 1.00%, Cr: 12.00 to 14.00%, P: 0.020% or less, S: 0.010% or less, N: 0.05% or less, O (Oxygen): 0.0060% or less, at least one alloying element selected from V, Nb and Ti of 0.005 to 0.200% and B of 0.0005 to 0.0100%, and the balance Fe and impurities, satisfying either the following inequalities (1), (2), (4) and (5) or the following inequalities (1), (3), (4) and (5): <?in-line-formulae description="In-line Formulae" end="lead"?>C*+10N*<=0.45, (1) <?in-line-formulae description="In-line Formulae" end="tail"?> <?in-line-formulae description="In-line Formulae" end="lead"?>H1<=-0.003(C*+10N*)+0.0016, (2) <?in-line-formulae description="In-line Formulae" end="tail"?> <?in-line-formulae description="In-line Formulae" end="lead"?>H2<=-0.0018(C*+10N*)+0.00096, (3) <?in-line-formulae description="In-line Formulae" end="tail"?> <?in-line-formulae description="In-line Formulae" end="lead"?>Cr*<=9.0, (4) <?in-line-formulae description="In-line Formulae" end="tail"?> <?in-line-formulae description="In-line Formulae" end="lead"?>S<=0.088N*+0.00056, (5)<?in-line-formulae description="In-line Formulae" end="tail"?>
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