Strain Rate and Temperature Dependence of Mechanical Properties and Failure Behavior of AA7075-T651
摘要
In this study, the tensile and fracture behavior of AA7075-T651 was investigated under different temperatures (room temperature to 300 °C) and strain rates (10−1 to 10−4 s−1). Tensile tests were done to obtain the ultimate tensile strength, yield strength, modulus of elasticity, % elongation, strain to failure, and plastic anisotropy ratio (r-value). The strain rate sensitivity of the alloy was also investigated. The fractographic study on the fracture surfaces of the tested samples was done using FESEM and optical microscopy to analyze the fracture behavior. It was found that with an increase in temperature, there was a gradual decrease in yield and ultimate strength values, while % elongation increases, and this effect became more pronounced at higher temperatures. It was observed that with a decrease in strain rate, the yield and ultimate strength values decrease while % elongation increases. The strain rate sensitivity reveals that the material exhibits increased sensitivity at higher temperatures. The Johnson Cook model was used to predict the stress–strain response, and it was found that the model fit showed good agreement with test conditions, validating its applicability for predicting the flow behavior of AA7075-T651. A difference in fracture mode was noticed for different strain rates in fractographic studies. At room temperatures, the brittle failure behavior of the alloy was more dominant, while at higher temperatures, a completely ductile fracture was observed.