Development of elasto-plastic-creep constitutional equation for a die casting alloy and validation of thermal stress analysis

摘要

In order to predict the residual stress in shape castings, elasto-plastic models have been used. However, these models are not able to express the recovery, which is a characteristic behavior of alloys at high temperature. This often causes over estimation of the residual stress of the castings. In this study, an elasto-plastic-creep model is developed to express the recovery of the casting during cooling. Under the conditions of some temperatures and strain rates, tensile tests were conducted to identify the creep properties. In order to validate the thermal stress analysis with the developed model, an original device, called "Equipped I-Beam Caster" was also developed to measure thermal stress and temperature of the JIS ADC12 (ISO Al Si 11 Cu3(Fe)) casting continuously during cooling. As a result, compared to the elasto-plastic model, the elasto-plastic-creep model predicts more accurately not only the thermal stress during cooling but also the residual stress.