| 摘要 |
PURPOSE:To obtain a steel for an oil well pipe having high strength and superior corrosion resistance by subjecting a steel having a specified composition and satisfying a specified relation among C, N and Cr to rapid heating, quenching and tempering. CONSTITUTION:A steel having a composition consisting of, by weight, <=0.22% C, <=0.80% Si, <=0.80% Mn, <=0.05% Cu, <=0.10% Ni, 12.0-14.5% Cr, <=0.10% Al, 0.005-0.100% N and the balance Fe with inevitable impurities or further contg. 0.01-0.15% Mo and/or 0.005-0.050% Nb and 0.01-0.10% V and/or 0.01- 0.10% Ti and satisfying an equation 100XC(%)+100XN(%)-2XCr(%)+9>=0 is refined and heat treated once or more by rapid heating to 940-1,050 deg.C, holding at the temp. for a short time and quenching. The steel is then tempered at the Ac1 point or below. At this time, rough tempering is carried out once or more after the quenching. |
