Strength of Materials After Severe and Complex Thermal Histories 610051
ACCURATE METHODS are needed for predicting the effect of severe thermal environments on the strength of flight vehicle materials. Most metallic materials for such applications derive a large part of their strength from a hardening treatment. The hardening mechanism becomes unstable at high temperatures and progressive changes occur which cause softening and strength reduction. Addition of stress during elevated temperature exposure can have an accelerating effect on this strength reduction. These permanent changes are additive to the recoverable losses in strength which all metals show with increasing temperature. If the effects of these variables on materials can be predicted for complex environments the useful temperature range can be extended.
This paper presents an approach for predicting cumulative losses in short time strength of many materials as a result of exposure to complex thermal and stress histories. This approach is based on rate process theory.