Abstract: To provide an austenitic stainless steel material having a high creep strength and a high creep ductility even in a high-temperature environment at 800° C. or more. An austenitic stainless steel material according to the present disclosure has a chemical composition that includes, in mass %: C: 0.060% or less; Si: 1.0% or less; Mn: 2.00% or less; P: 0.0010 to 0.0400%; S: 0.010% or less; Cr: 10 to 25%; Ni: 25 to 45%; Nb: 0.2 to 2.0%; W: 2.5 to 6.0%; B: 0.0010 to 0.0100%: Al: 2.5 to 4.5%; and the balance being Fe and impurities, and satisfies Formulae (1) and (2), and the sum of the content of dissolved Nb and the content of dissolved W is 3.2 mass % or more. (W/184+Nb/93)/(C/12)?5.5??(1) (W/184+Nb/93)/(B/11)?450??(2) In Formulae (1) and (2), the content in mass % of the corresponding element is substituted for each symbol of element.

Abstract: To provide an austenitic stainless steel material having a high creep strength and a high creep ductility even in a high-temperature environment at 800° C. or more. An austenitic stainless steel material according to the present disclosure has a chemical composition that includes, in mass %: C: 0.060% or less; Si: 1.0% or less; Mn: 2.00% or less; P: 0.0010 to 0.0400%; S: 0.010% or less; Cr: 10 to 25%; Ni: 25 to 45%; Nb: 0.2 to 2.0%; W: 2.5 to 6.0%; B: 0.0010 to 0.0100%: Al: 2.5 to 4.5%; and the balance being Fe and impurities, and satisfies Formulae (1) and (2), and the sum of the content of dissolved Nb and the content of dissolved W is 3.2 mass % or more. (W/184+Nb/93)/(C/12)?5.5??(1) (W/184+Nb/93)/(B/11)?450??(2) In Formulae (1) and (2), the content in mass % of the corresponding element is substituted for each symbol of element.

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: There is provided an austenitic alloy pipe that is durable even if a stress distribution different according to usage environment is applied. The austenitic alloy pipe in accordance with the present invention has a tensile yield strength YSLT of at least 689.1 MPa. The tensile yield strength YSLT, a compressive yield strength YSLC in a pipe axial direction, a tensile yield strength YSCT in a pipe circumferential direction of the alloy pipe, and a compressive yield strength YSCC in the pipe circumferential direction satisfy Formulas (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.

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: There is provided an austenitic alloy pipe that is durable even if a stress distribution different according to usage environment is applied. The austenitic alloy pipe in accordance with the present invention has a tensile yield strength YSLT of at least 689.1 MPa. The tensile yield strength YSLT, a compressive yield strength YSLC in a pipe axial direction, a tensile yield strength YSCT in a pipe circumferential direction of the alloy pipe, and a compressive yield strength YSCC in the pipe circumferential direction satisfy Formulas (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.

Abstract: The invention provides an eddy current testing method for an internal finned pipe or tube which can securely detect a micro defect generated in a trough portion in an inner surface of the pipe or tube, even in the case that an inner surface shape of the internal finned pipe or tube is ununiform in a circumferential direction of the pipe or tube. The eddy current testing method in accordance with the invention detects a defect existing in a trough portion of the pipe or tube (P) by arranging a differential coil (2) constructed by a pair of coils (21, 22) having such a dimension as to be arranged within the trough portion of the pipe or tube (P) and coming away from each other in an axial direction (X) of the coil, within the trough portion of the pipe or tube (P) along a direction in which the trough portion of the pipe or tube (P) extends, and relatively moving the differential coil (2) in the direction in which the trough portion of the pipe or tube (P) extends.

Abstract: The invention provides an eddy current testing method for an internal finned pipe or tube which can securely detect a micro defect generated in a trough portion in an inner surface of the pipe or tube, even in the case that an inner surface shape of the internal finned pipe or tube is ununiform in a circumferential direction of the pipe or tube. The eddy current testing method in accordance with the invention detects a defect existing in a trough portion of the pipe or tube (P) by arranging a differential coil (2) constructed by a pair of coils (21, 22) having such a dimension as to be arranged within the trough portion of the pipe or tube (P) and coming away from each other in an axial direction (X) of the coil, within the trough portion of the pipe or tube (P) along a direction in which the trough portion of the pipe or tube (P) extends, and relatively moving the differential coil (2) in the direction in which the trough portion of the pipe or tube (P) extends.