Effect of Strain Aging on Strengthening of 25Ni Maraging Steel Containing Co and Mo

Abstract

In order to strengthen 25Ni maraging steel containing Be, Ti and Al, effects of combined additions of Co and Mo, and strain aging have been investigated.
For 23.5Ni-9.1Co-5.3Mo-0.68Be-0.30Ti-0.25Al alloy, 295 kg/mm² tensile strength and 1.7% elongation are obtained by aging treatment at 450°C for 1 hr after cold working with 64% reduction of area. Dilation, electrical resistance and specific heat measurements reveal that there is no essential difference in the aging behavior between conventional aging and strain aging. But precipitation and austenite reversion can occur in strain aging at a temperature lower than 30°C in conventional aging.