The Role of Creep Recovery in the Static-to-Dynamic Transition of Creep

Abstract

A phenomenological theory was developed to describe the static-to-dynamic transition in creep of metals reported in the preceding report with a good agreement with the experiment. The theory is essentially one of interaction of creep and creep recovery, ant it is based on the following two fundamental features: first, the total strain under creep condition can not be regarded as the sum of the three mutually independent components, i. e. elastic, anelastic (creep recovery) and plastic (creep) strains as has usually been done. There is a strong interaction between the anelastic and the creep strains. Secondly, the creep recovery under load-off condition does not appear to be simply the inverse of the anelastic creep under load-on condition as has so far been thought. The delay time for the load-off condition seems to be much longer than that for the load-on condition. It is also to be noted that the rate of creep recovery immediately after unloading is approximately equal to the creep rate during the load-on period. Much more works are desired to be done on the creep recovery not only because of its importance in connection with the creep behavior under cyclic stress condition but also because it is possibly related with the mechanism of creep in general.