Strengthening of 18%Ni maraging steels by cold rolling after pre-aging and re-aging

Thermomechanical treatments for improving tensile strength of 18% Ni maraging steels have been investigated. The thermomechanical treatments applied to the 210 kg/mm2 and 245 kg/mm2 grades maraging steels include a) cold rolling and aging, b) cold rolling in preaged conditions with and without subsequent re-aging at about 5000C. Increases in strength produced by cold rolling and aging are given as a function of the reduction in thickness. The tensile strength in the transvers direction reaches to a peak and then decreases because of the drop in elongation. The increase in strength produced by cold rolling in the pre-aged conditions is small. However, the tensile strength is greatly increased by the subsequent re-aging. The tensile strength in the transverse direction is remarkably improved by a thermomechanical treatment including preaging at 5000C, cold rolling, and re-aging at about 5000C. (auth.)