LOW-ALLOY TEMPERED FORGED STEEL EXCELLENT IN FALLING WEIGHT CHARACTERISTICS

摘要

PURPOSE:To obtain a low-alloy tempered forged steel having superior toughness at low temp. when used as thick-walled material by incorporating specific percentage of C, Mn, Cr, Ni, Mo, Al, N, S, Si, and P to Fe. CONSTITUTION:The low-alloy tempered forged steel which consists of, by weight, 0.05-0.15% C, =0.60% Mn, 1.50-2.50% Cr, 3.00-4.00% Ni, 0.30-0.60% Mo, 0.006-0.060% Al, 0.0015-0.0150% N, =0.020% S and the balance Fe with inevitable impurities and in which Si and P content is regulated so that 50(%Si)+600(%P) is =16% is prepared. This steel has such a superior toughness at low temp. as to give an NDT temp. of =about -100 deg.C by a drop-hammer test even used as a thick-walled material of =150mm thickness.