| 摘要 |
PURPOSE:To manufacture a high-tension low-alloy steel pipe with superior weldability by subjecting a low-alloy steel pipe contg. specified percentages of C, Si, Mn, Cr, Mo and V to heating, normalizing and tempering under specified conditions. CONSTITUTION:A low-alloy steel pipe consisting of 0.25-0.35% C, 0.40-0.80% Si, 0.40-1.00% Mn, 0.9-1.60% Cr, 0.30-0.70% Mo, 0.10-0.40% V and the balance Fe is heated to about 900-950 deg.C to austenitize the structure. The pipe is normalized at 3,000-6,500 deg.C/hr cooling rate, and it is tempered at 500-650 deg.C. A high-tension low-alloy steel pipe having favorable surface properties, high dimensional accuracy and superior tensile strength such as >=120kg/mm.<2> is obtd. |
