Dual phase stainless steel pipe and manufacturing method thereof
View Patent ↗A dual phase stainless steel pipe includes tensile yield strength YS LT of 689.1 MPa to 1000.5 MPa in a pipe axis direction of the dual phase stainless steel pipe, in which the tensile yield strength YS LT , a compressive yield strength YS LC in the pipe axis direction, a tensile yield strength YS CT in a pipe circumferential direction of the dual phase stainless steel pipe, and a compressive yield strength YS CC in the pipe circumferential direction satisfy all Expressions (1) to (4), 0.90≤YS LC /YS LT ≤1.11 (1) 0.90≤YS CC /YS CT ≤1.11 (2) 0.90≤YS CC /YS LT ≤1.11 (3) 0.90≤YS CT /YS LT ≤1.11 (4).
1. A dual phase stainless steel pipe, comprising:
a tensile yield strength YS LT of 689.1 MPa to 1000.5 MPa in a pipe axis direction of the dual phase stainless steel pipe,
wherein the tensile yield strength YS LT , a compressive yield strength YS LC in the pipe axis direction, a tensile yield strength YS CT in a pipe circumferential direction of the dual phase stainless steel pipe, and a compressive yield strength YS CC in the pipe circumferential direction satisfy all Expressions (1) to (4),
the dual phase stainless steel pipe has a dual phase structure of austenite and ferrite,
the dual phase stainless steel pipe is manufactured by performing a straightening and a low temperature heat treatment at a heat treatment temperature of 350° C. to 450° C. after being subjected to cold working, and
a maximum crash ratio during the straightening is 2.0 to 15.0%,
0.90≤YS LC /YS LT ≤1.11 (1)
0.90≤YS CC /YS CT ≤1.11 (2)
0.90≤YS CC /YS LT ≤1.11 (3)
0.90≤YS CT /YS LT ≤1.11 (4).
2. The dual phase stainless steel pipe according to claim 1 ,
wherein the dual phase stainless steel pipe contains, in mass %,
C: 0.008% to 0.03%;
Si: 0% to 1%;
Mn: 0.1% to 2%;
Cr: 20% to 35%;
Ni: 3% to 10%;
Mo: 0% to 4%;
W: 0% to 6%;
Cu: 0% to 3%; and
N: 0.15% to 0.35%, and
a remainder composed of Fe and impurities.
3. The dual phase stainless steel pipe according to claim 1 ,
wherein the dual phase stainless steel pipe is manufactured by performing the low temperature heat treatment after the straightening.
4. The dual phase stainless steel pipe according to claim 2 ,
wherein the dual phase stainless steel pipe is manufactured by performing a straightening and a low temperature heat treatment at a heat treatment temperature of 350° C. to 450° C. after being subjected to cold working.
5. The dual phase stainless steel pipe according to claim 4 ,
wherein the dual phase stainless steel pipe is manufactured by performing the low temperature heat treatment after the straightening.
6. The dual phase stainless steel pipe according to claim 1 ,
wherein the tensile yield strength YS CT in a pipe circumferential direction of the dual phase stainless steel pipe, and the compressive yield strength YS CC in the pipe circumferential direction satisfy 0.90≤YS CC /YS CT ≤1.04.