Abstract: A Ni-based alloy tube includes a base metal having a chemical composition consisting, by mass percent, of C: 0.15% or less, Si: 1.0% or less, Mn: 2.0% or less, P: 0.030% or less, S: 0.030% or less, Cr: 10.0 to 40.0%, Ni: 50.0 to 80.0%, Ti: 0.50% or less, Cu: 0.60% or less, Al: 0.20% or less, N: 0.20% or less, and the balance: Fe and impurities; and a low Cr content complex oxide film having a thickness of 25 nm or smaller at least on an inner surface of the base metal, wherein contents of Al, Ni, Si, Ti, and Cr in the film satisfy [at % Al/at % Cr?2.00], [at % Ni/at % Cr?1.40], and [(at % Si+at % Ti)/at % Cr?0.10].

Abstract: An austenitic alloy tube subjected to a cold working and an annealing heat treatment contains C: 0.01% to 0.15%, Cr: 10.0% to 40.0%, Ni: 8.0% to 80.0%, in mass %, and has a metallographic structure satisfying the following Expressions (i) to (iii). R?f1??(i) R=I220/I111??(ii) f1=0.28×(F1118.0/(F1118.0+0.358.0))??(iii) Where, in the above Expressions, R is a ratio of an integrated intensity of {220} to an integrated intensity of {111} on a surface layer which is measured by a grazing incidence X-ray diffraction method, I220 is the integrated intensity of {220}, I111 is the integrated intensity of {111}, and F111 is full width of half maximum of {111} on the surface layer which is measured by the grazing incidence X-ray diffraction method.

Abstract: A Ni-based alloy tube includes a base metal having a chemical composition consisting, by mass percent, of C: 0.15% or less, Si: 1.0% or less, Mn: 2.0% or less, P: 0.030% or less, S: 0.030% or less, Cr: 10.0 to 40.0%, Ni: 50.0 to 80.0%, Ti: 0.50% or less, Cu: 0.60% or less, Al: 0.20% or less, N: 0.20% or less, and the balance: Fe and impurities; and a low Cr content complex oxide film having a thickness of 25 nm or smaller at least on an inner surface of the base metal, wherein contents of Al, Ni, Si, Ti, and Cr in the film satisfy [at % Al/at % Cr?2.00], [at % Ni/at % Cr?1.40], and [(at % Si+at % Ti)/at % Cr?0.10].

Abstract: An austenitic alloy tube subjected to a cold working and an annealing heat treatment contains C: 0.01% to 0.15%, Cr: 10.0% to 40.0%, Ni: 8.0% to 80.0%, in mass %, and has a metallographic structure satisfying the following Expressions (i) to (iii). R?f1??(i) R=I220/I111??(ii) f1=0.28×(F1118.0/(F1118.0+0.358.0))??(iii) Where, in the above Expressions, R is a ratio of an integrated intensity of {220} to an integrated intensity of {111} on a surface layer which is measured by a grazing incidence X-ray diffraction method, I220 is the integrated intensity of {220}, I111 is the integrated intensity of {111}, and F111 is full width of half maximum of {111} on the surface layer which is measured by the grazing incidence X-ray diffraction method.