The Effect of Hydrostatic Stress on Creep and the Creep Rupture of Polycrystalline Metals at Elevated Temperatures

Abstract

In the present paper, the analytical and experimental studies on tensile creep of polycrystalline metal under hydrostatic pressure at elevated temperatures were presented, in a series of studies on the influence of hydrostatic stress on plasticity and fracture laws of the metals. From the tests performed of commercial pure aluminum at 200°C, the following conclusion has been derived.(1) The effect of hydrostatic pressure on minimum creep rate at elevated temperature is more intensive than that on tensile flow stress at the same temperature. This is considered to be mainly due to the pressure on the diffusion of vacancies in the creep process.(2) In order to predict the effect of hydrostatic stress on the creep rupture of the metal at elevated temperature from that on the steady state creep at the same temperature, it is required that the pressure effect on the structural change during the tertiary creep, such as inhibition of growth of void as the result of reduction in the diffusion of vacancies will be taken into consideration.