On the nature of latent period of delayed destruction in quenched steel

The destructive influence of applied stress on the delayed destruction of quenched steel is investigated. Stress loading beyond a fixed value results in delayed destruction. The threshold stress point G at which delayed destruction occurs is shown to be near the elastic limit value of the steel. If during the incubation period quenched steels are exposed to preliminary stress above the threshold point, then the relaxation process is slowed down, while the tendency to delayed destruction is increased. It is supposed that such an exposure during the incubation period results in relaxation of the internal residual microstresses which leads to the formation of defects, such as micro-cracks