A two step heat treatment for Ni--Cr--Mo alloys containing from 12% to 23.5% chromium provides higher yield strength, high tensile strength and other mechanical properties comparable to those observed in similar alloys age-hardened according to current practices. This treatment is done over a total time of not more than 50 hours. However, the treatment works for only those alloys having alloying elements present in amounts according to an equation here disclosed.