Sumitomo Metal Industries, Inc.

Shigeru Kidani

Mutsumi Tanida

Toshiharu Abe

Koichi Ikeda

The present invention provides a martensitic stainless steel seamless pipe and a method of making, wherein the pipe has minimal inner surface defects and prevents delayed fracture generation in the impact-worked portions. The pipe comprises 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, wherein either the following inequalities (1), (2), (4) and (5) or the following inequalities (1), (3), (4) and (5) are satisfied:C*+10N*&#x2266;0.45,&#x2003;&#x2003;(1)H1&#x2266;&#x2212;0.003(C*+10N*)+0.0016,&#x2003;&#x2003;(2)H2&#x2266;&#x2212;0.0018(C*+10N*)+0.00096,&#x2003;&#x2003;(3)Cr*&#x2266;9.0,&#x2003;&#x2003;(4)S&#x2266;0.088N*+0.00056,&#x2003;&#x2003;(5).

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Kainan, Japan

Shigeru Kidani