S816の高温機械的性質に関する研究(I)

Abstract

The authors studied the effect of solution-treatment temperature and aging on the creep rupture characteristics at 732°C and 26.6kg/mm2. The results are as follows:(1) Creep resistance increased by increasing solution-treatment temperature from 1150°C to 1250°C, because the carbide dissolves in matrix by high-temperature solution-treatment and fine carbides precipitated during high-temperature creep-rupture test. But creep-rupture life decreased by solution treatment at 1250°C if abnormal grain growth occurred by this treatment.(2) Creep ductility was not evidently affected by solution-treatment temperature, but it decreased by solution-treatment at 1250°C by the fact that the precipitation increased and that the grain size became coarser.(3) Creep resistance decreased by aging when the specimens were solution-treated below 1225°C, but the difference of creep resistance between the specimen aged and not aged, disappeared when they were solution treated at 1250°C. Precipitation hardening in the specimens solution treated at 1250°C was greater than the specimen solution treated at lower temperature, so the effect of aging before creep-rupture test had no effect on precipitation hardening during creep-rupture test, so creep resistance was not affected by aging. But precipitation hardening during creep rupture test decreased by aging before creep-rupture test in the specimens solution-treated at lower temperature, because preeipitation hardening was small originally at that condition, so creep-resistance decreased by aging.(4) Creep ductility was not evidently affected by aging, but ductility of as solution-treated specimens were inferior to the ductility of the specimens of as solution-trbated and aged, because precipitation hardening was greater in the former cases than the latter cases. These difference of ductility was more evident at the higher-temperature solution-treated specimens than the lower-temperature solution-treated specimens.