Study On Fracture Behavior Of 7A04 Aluminum Alloy Sheet In Hot Stamping

In recent years,the lightweight of automobiles has become one of the main trends in the development of the automotive industry.Aluminum alloy has become one of the most ideal materials in automotive lightweight technology due to its advantages such as high specific strength,high specific stiffness,good impact resistance and corrosion resistance.7A04 aluminum alloy belongs to the Al-Zn-Mg-Cu series high-strength aluminum alloys.Due to its low room temperature plastic elongation,it is prone to fracture in traditional cold stamping,which limits its application in the automotive field.The use of aluminum alloy hot stamping technology can effectively solve this problem.Therefore,studying the hot formability of aluminum alloys and predicting the high-temperature fracture of aluminum alloys is of great significance for guiding product process design.This article focuses on the rheological behavior and damage fracture mechanism of 7A04 aluminum alloy under high-temperature conditions.The main work is as follows:Five specimens with different shapes were designed to conduct high-temperature Tensile testing at 350℃～450℃ on 7A04 aluminum alloy plates.The mechanical properties and fracture behavior characteristics of 7A04 aluminum alloy under different deformation temperatures,different strain rates and different stress states were obtained.The fracture morphology of the sample was observed by Scanning electron microscope.The analysis showed that the fracture mechanism of 7A04 aluminum alloy during hightemperature deformation was the ductile fracture.Based on the high-temperature rheological Stress-strain curve obtained from the test,and considering the effects of deformation temperature and strain rate on the deformation of 7A04 aluminum alloy,the Arrhenius high-temperature constitutive model of the material was established.The fracture parameters of 7A04 aluminum alloy under different experimental conditions were obtained by combining experiments and simulations.Based on the obtained fracture parameters,the coefficients in the fracture model were calibrated,and a Johnson-Cook fracture model of 7A04 aluminum alloy was established.Apply the established Johnson-Cook fracture model of 7A04 aluminum alloy to predict the damage and fracture phenomenon during the hot stamping process of cylindrical parts.The reliability and accuracy of the model were verified by comparing experimental results with simulation predictions.The results indicate that the established fracture model can accurately predict the damage and fracture behavior of 7A04 aluminum alloy during hot stamping forming.