オーステナイト系Ni-Cr鋼の歪時効硬化の性状について

Abstract

The strain age hardening of austenitic Ni-Cr steels was studied chiefly by the comparison between the one-phase alloy and two-phase alloys containing martensite. The results obtained were as follows. (1) The strain age hardening occurs in two stages on annealing below 475°C after cold work, and there seems to be no difference in the nature of the hardenings between the one-phase and the two-phase alloys. (2) The strain age hardening is as hardly accompanied by a rise of yield point as in the cases of carbon steels and copper alloys, when measured under a stress of the same kind and direction as those of prior working, probably indicating that the rise is directional. (3) The degrees of strain age hardening and inelastic effect observed on unloading after extension are approximately proportional to f3⁄2 in the range where the volume fraction of martensite (f) is relatively small, leading to the presumption that the hardening is closely related with the pile-up dislocation and the back stress.