A STAINLESS STEEL PIPE AND AN OIL WELL PIPE COMPRISING SAID STAINLESS STEEL PIPE

Claims

An object of the present invention is to provide a stainless steel tube with high strength and excellent resistance to hydrogen embrittlement. The expression “excellent resistance to hydrogen embrittlement” means that, in a hydrogen-loaded tensile test, the elongation after fracture is 9.0% or more and that, in the tensile test, where the horizontal axis represents true stress, the vertical axis represents true strain, and true stress at maximum load is denoted by εmax, a rate of change d²σ / dε² of a work-hardening rate dσ / dε with respect to ε is -200,000 MPa or more in a true stress range of 0.8 εmax or more and εmax or less. The symbol σ denotes true strain (MPa), and ε denotes true stress (dimensionless). The term “high strength” refers to a yield strength of 450 MPa or more.The stainless steel tube has a specific microstructure, in which an average KAM value, which is an average of a KAM (average center misorientation) value of the steel microstructure, is 2.0º or more and 4.0º or less, and a standard deviation of a distribution of the KAM value is 1.5º or less.