Abstract
Recently the heat resisting alloys have made remarkable developments. There are few differences in the essential consideration of chemical constituents, but the aging time has been so prolonged that the stability of structure and strength at elevated temperature much increased. In heat-resisting alloys, some phenomena such as creep and fatigue take place under repeated stresses during practical use.
The transformation and precipitation of the alloys are accelerated by these repeated stresses so that there occurs a change of the volume and a decrease in the creep or the fatigue strength.
Further, a systematic research on these problems is needed. It is also presumed neccessary that new manufacturing techniques, for example, vacuum-melting, vacuum-casting and hotextrusion should be introduced for further improvements in heat resisting alloys.
