Plasticity Ratio–based post-processing for predicting hot forging die life: Industrial validation for gas-nitrided AISI H13 tools
摘要
The service life of hot forging dies is limited by severe thermomechanical loading that promotes localized plastic deformation, wear, and crack initiation. Conventional numerical assessments are commonly based on equivalent stress fields, which do not explicitly consider the temperature-dependent reduction of tool material strength, often leading to limited correlation between predicted critical regions and actual industrial failure locations. This work proposes a mechanically grounded post-processing methodology based on the Plasticity Ratio, defined as the ratio between effective stress and temperature-dependent yield strength, to evaluate local proximity to plastic yielding. The approach integrates thermomechanical finite element simulations, experimentally measured microhardness profiles, and industrial validation. Applied to gas-nitrided AISI H13 finishing dies, the method incorporates the hardness gradient of the diffusion zone through a resistance increment factor (