Mechanical properties of the alloy 36NKhTYu in relation to the mechanisms underlying the precipitation of the γ′ and η phases. III

The kinetic characteristics of the changes in elastic limit, ductility, and stress relaxation taking place in samples of the alloy 36NKhTYu on aging at 700°C are considered in relation to aging time, the measurements being made at 20 and 600°C. The samples are initially taken in five different states induced by various forms of preliminary treatment, being distinguished from one another with respect to grain size, mechanism of γ phase precipitation, and state of the grain boundaries. In order to obtain material with a high elastic limit, working at moderately low temperatures, the discontinuous precipitation of the strengthening phase has certain clear advantages over continuous precipitation. For high working temperatures, in which grain-boundary stress relaxation starts playing an appreciable role, however, it is undesirable that discontinuous decomposition should undergo any major development in the aging of the material.