Patent ID: 11286548

Abstract:
The invention is intended to provide a high-strength stainless steel seamless pipe for oil country tubular goods having high strength with a yield strength of 862 MPa (125 ksi) or more, excellent low-temperature toughness, and excellent corrosion resistance. The invention is also intended to provide a method for manufacturing such a high-strength stainless steel seamless pipe. The high-strength stainless steel seamless pipe has a microstructure that is at least 45% tempered martensite phase, 20 to 40% ferrite phase, and more than 10% and 25% or less retained austenite phase by volume. The high-strength stainless steel seamless pipe has a yield strength of 862 MPa or more, and a maximum crystal grain diameter of 500 μm or less for ferrite crystal grains when crystal grains with a crystal orientation difference of within 15° are defined as the same crystal grains.