Abstract: There is provided an austenitic heat resistant alloy having a chemical composition that contains, in mass percent: C: 0.03 to 0.25%, Si: 0.01 to 2.0%, Mn: 0.10 to 0.50%, P: 0.030% or less, S: 0.010% or less, Cr: 13.0 to 30.0%, Ni: 25.0 to 45.0%, Al: 2.5 to 4.5%, Nb: 0.01 to 2.00%, N: 0.05% or less, Ti: 0 to 0.20%, W: 0 to 6.0%, Mo: 0 to 4.0%, Zr: 0 to 0.10%, B: 0 to 0.0100%, Cu: 0 to 5.0%, REM: 0 to 0.10%, Ca: 0 to 0.050%, Mg: 0 to 0.050%, and the balance: Fe and impurities.

Abstract: A duplex stainless steel with occurrence of pitting suppressed is provided. A duplex stainless steel according to the present disclosure has a chemical composition consisting of, in mass %, Cr: more than 27.00% to 29.00%, Mo: 2.50 to 3.50%, Ni: 5.00 to 8.00%, W: 4.00 to 6.00%, Cu: 0.01 to less than 0.10%, N: more than 0.400% to 0.600%, C: 0.030% or less, Si: 1.00% or less, Mn 1.00% or less, sol.Al: 0.040% or less, V: 0.50% or less, O: 0.010% or less, P: 0.030% or less, and S: 0.020% or less with the balance being Fe and impurities and satisfying Formula (1), a microstructure consisting of 35 to 65 volume % of ferrite phase with the balance being the austenite phase, and the area fraction of Cu precipitated in the ferrite phase is 0.5% or less. Cr+4.0×Mo+2.0×W+20×N?5×ln(Cu)?65.

Abstract: A dual phase stainless steel pipe includes tensile yield strength YSLT 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 YSLT, a compressive yield strength YSLC in the pipe axis direction, a tensile yield strength YSCT in a pipe circumferential direction of the dual phase stainless steel pipe, and a compressive yield strength YSCC in the pipe circumferential direction satisfy all Expressions (1) to (4), 0.90?YSLC/YSLT?1.11??(1) 0.90?YSCC/YSCT?1.11??(2) 0.90?YSCC/YSLT?1.11??(3) 0.90?YSCT/YSLT?1.11??(4).

Abstract: A dual phase stainless steel pipe includes tensile yield strength YSLT 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 YSLT, a compressive yield strength YSLC in the pipe axis direction, a tensile yield strength YSCT in a pipe circumferential direction of the dual phase stainless steel pipe, and a compressive yield strength YSCC in the pipe circumferential direction satisfy all Expressions (1) to (4), 0.90?YSLC/YSLT?1.11??(1) 0.90?YSCC/YSCT?1.11??(2) 0.90?YSCC/YSLT?1.11??(3) 0.90?YSCT/YSLT?1.11??(4).