MANUFACTURE OF 18 NI MARAGING STEEL

摘要

PURPOSE:To improve the strength without deteriorating tensile strength, notch strength and high ductility, by performing the soln. treatment after heat working the titled steel contg. trace B by dividing it to 2 times at high and low temp. ranges. CONSTITUTION:To conventional 18% Ni maraging steel, =0.005wt% B is added and incorporated. Said steel is hot worked usually at 600-1,200 deg.C range in hot working, soln. treating and aging thereof. In this case, said steel is hot worked at temp. range excluding 800-900 deg.C range, and at least =1 pass of the hot working is carried out at =900 deg.C by =20% draft per one pass. In next soln. treatment, at first, said material is soln. treated primarily at 930-1,050 deg.C range, cooled then soln. treated secondarily at 750-850 deg.C range, at last, aged to manufacture the titled steel superior in both toughness and strength.