A process design CAE system that can predict the die life of a hot forging die has been developed. The main frame of the system consists of four parts: (1) a stress and thermal load analysis, (2) calculation of tempering parameter of die steel and of hardness at necessary die life, (3) plotting results on the surface damage map, and (4) estimation of surface damage by the map to judge the designs for necessary die life.

In order to relate the failures in die life and the parameters calculated by CAE, a surface damage map is proposed. The map has two axes, one represents the degree of degradation of the die steel, and the other represents the frictional severity. The degree of degradation is defined by the ratio of the yield shear stress to the friction shear stress and the frictional severity is defined by the cumulative friction work, where the yield shear stress is the high-temperature value after softening caused by repeated forging. To achieve these estimations, the system stored database of tempering property and high-temperature strength of die steels. This system can be utilized for improvement of process design.
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