INTERPRETATION OF RESPONSE TO SUDDEN TEMP ERATURE-CHANGE BY MEANS OF THE MODEL OF HARD AND SOFT REGIONS

The composite model of plastic deformation of material consisting of h ard and soft regions is used to simulate a technique of sudden tempera ture changes performed in creep. The model characterizes a subgrain st ructure typical of high temperature creep. The contribution of subgrai n boundary migration to the total strain rate is included in the model and thus a prediction of behaviour of structure quantities is enabled . It is shown that following an increase in temperature the increased creep rate gradually falls down. This effect is in accord with experim ental observations whereas it cannot be explained by a simple applicat ion of the internal stress concept.