Sensitivity Effect of Thermal Expansion Coefficient on Combined Stress of Hot Forging Die

Abstract

Stresses, including thermal, mechanical and combined stress, are the root causes leading to hot forging die failure. Stress amplitude is affected by the material properties, such as thermal expansion coefficient. In order to select die material for improving die service life, a 2D FE model is developed to analyze thermal, mechanical and combined stress of hot forging die with different level thermal expansion coefficient. Three kinds of stress distribution are explored. The results show that thermal stress is about 10 times than mechanical stress at the die cavity surface which is the easiest failure location, and approximate linear relationship exists between stress, including thermal and combined stress, and thermal expansion coefficient. Die material with small room temperature and temperature-sensitive thermal expansion coefficient should be selected.