Patent ID: 6846371

Claim:
A method for making a high-strength high-toughness martensitic stainless steel seamless pipe comprising: heating a martensitic stainless steel raw material to an austenitic range; piercing and elongating the raw material to form an original pipe; cooling the original pipe to form a structure substantially composed of martensite in the original pipe; reheating the original pipe to a temperature in a dual-phase range between the A c1 transformation point and the A c3 transformation point directly after cooling the original pipe to form the structure substantially composed of martensite; finish-rolling the original pipe at an initial rolling temperature T (° C.) between the A c1 transformation point and the A c3 transformation point; cooling the original pipe to form a processed pipe having a predetermined size; and tempering the processed pipe at a temperature below the A c1 transformation point.