Material-related model for thermal fatigue applied to tool steels in hot-work applications

Abstract

A material-related model for thermal fatigue is presented and discussed in connection with tool steels in hot-work applications. The model, which is based on ordinary ‘fatigue laws’, includes a simplified stress/strain analysis for the general thermal fatigue case. From this analysis expressions are generated which relate crack initiation and growth processes to important material as well as process variables in a quantitative manner. Furthermore, thermal fatiguemechanism maps are introduced. The possible utilization of such maps is demonstrated and discussed with reference mainly to hot-work tool steels. Mechanism maps of this kind may offer, among other things, help in selecting materials for various applications where thermal fatigue is to be expected.