Patent ID: 11970759
Assignee: NIPPON STEEL CORPORATION
Field: Materials, metallurgy (Chemistry)
Classification: CPC C | IPC C

Claim 0:
1. A martensitic stainless seamless steel pipe comprising:
a chemical composition consisting of, in mass %,
C: 0.030% or less,
Si: 1.00% or less,
Mn: 1.00% or less,
P: 0.030% or less,
S: 0.0050% or less,
Al: 0.001 to 0.100%,
N: 0.0500% or less,
0: 0.050% or less,
Ni: 5.00 to 6.50%,
Cr: more than 10.00 to 13.40%,
Cu: more than 1.50 to 3.50%,
Mo: 1.00 to 4.00%,
V: 0.01 to 1.00%,
Ti: 0.050 to 0.300%,
Co: 0.010 to 0.300%,
Ca: 0 to 0.0035%,
W: 0 to 1.50%, and
Ta: 0 to 0.50%,
with the balance being Fe and impurities, and satisfying Formula (1):

Cr+2.0Mo+0.5Ni+2.0Cu+0.5Co≥20.0  (1)

where, a content of a corresponding element, in mass %, is substituted for each symbol of an element in Formula (1),
wherein an inner surface of the martensitic stainless seamless steel pipe has a depassivation pH of 3.00 or less in an aqueous solution that contains 5 mass % of NaCl, 0.41 g/L of CH3COONa, and CH3COOH.