US 12,291,766 B2
Stainless steel seamless pipe and method for manufacturing same
Yuichi Kamo, Tokyo (JP); and Masao Yuga, Tokyo (JP)
Assigned to JFE STEEL CORPORATION, Tokyo (JP)
Appl. No. 17/764,649
Filed by JFE STEEL CORPORATION, Tokyo (JP)
PCT Filed Aug. 27, 2020, PCT No. PCT/JP2020/032406
§ 371(c)(1), (2) Date Mar. 29, 2022,
PCT Pub. No. WO2021/065262, PCT Pub. Date Apr. 8, 2021.
Claims priority of application No. 2019-181341 (JP), filed on Oct. 1, 2019.
Prior Publication US 2022/0349036 A1, Nov. 3, 2022
Int. Cl. C22C 38/48 (2006.01); C21D 8/10 (2006.01); C21D 9/08 (2006.01); C22C 38/12 (2006.01); C22C 38/42 (2006.01); C22C 38/44 (2006.01); C22C 38/46 (2006.01)
CPC C22C 38/48 (2013.01) [C21D 8/105 (2013.01); C21D 9/085 (2013.01); C22C 38/12 (2013.01); C22C 38/42 (2013.01); C22C 38/44 (2013.01); C22C 38/46 (2013.01); C21D 2211/001 (2013.01); C21D 2211/005 (2013.01); C21D 2211/008 (2013.01)] 16 Claims
 
1. A stainless steel seamless pipe having a composition that comprises, by mass %:
C: 0.06% or less;
Si: 1.0% or less;
P: 0.05% or less;
S: 0.005% or less;
Cr: more than 15.8% and 18.0% or less;
Mo: 1.8% or more and 3.5% or less;
Cu: more than 1.5% and 3.5% or less;
Ni: 2.5% or more and 6.0% or less;
V: 0.01% or more and 0.5% or less;
Al: 0.10% or less;
N: 0.10% or less;
O: 0.010% or less;
Ta: 0.001% or more and 0.3% or less; and
the balance being Fe and incidental impurities,
wherein:
C, Si, Mn, Cr, Ni, Mo, Cu, and N satisfy formula (1):
13.0≤−5.9×(7.82+27C−0.91Si+0.21Mn−0.9Cr+Ni−1.1Mo+0.2Cu+11N)≤50.0  (1),
where C, Si, Mn, Cr, Ni, Mo, Cu, and N in the formula (1) represent the content, by mass %, of each element in the composition, and the content of any elements that are not contained in the composition is 0 mass %,
the stainless steel seamless pipe has a microstructure containing at least 30% martensitic phase, at most 60% ferrite phase, and at most 40% retained austenite phase by volume,
the stainless steel seamless pipe has a yield strength of 758 MPa or more, and
the composition does not contain W.