STAINLESS STEEL AND ARTICLE FROM STAINLESS STEEL FOR OIL WELL Russian patent published in 2019 - IPC C22C38/00 

FIELD: metallurgy.

SUBSTANCE: invention relates to ferrous metallurgy. Stainless steel has a matrix structure which contains in volume ratio from 40 to 80 % of tempering martensite, from 10 to 50 % of ferrite and from 1 to 15 % of austenite. When microstructure image with size of 1 mm × 1 mm, obtained by photographing the matrix structure with 100-fold magnification, is placed in the xy-coordinate system with the x-axis extended along the wall thickness direction and the y-axis extended along the length direction, and each of 1024×1024 pixels is represented by gray scale level, value β, defined by expression (2), is not less than 1.55.

EFFECT: achieving good corrosion resistance and low-temperature impact viscosity.

6 cl, 9 dwg, 3 tbl