Hot tensile deformation behavior and microstructure evolution of 7075 aluminum alloy sheet

The hot tensile deformation behavior of 7075 aluminum alloy sheet was studied using Gleeble-3800 thermal simulation machine at deformation temperatures of 400-475 degrees C and strain rates of 0.001 similar to 1s(-1). Microstructure evolution and fracture morphology were observed by optical microscopy (OM), scanning electron microscopy (SEM) and trans-mission electron microscopy (TEM). The hyperbolic sine model is used to establish the constitutive equation of the relationship between peak stress and Z parameter. The results show that the hyperbolic sine Arrhenius constitutive equation can well characterize the flow behavior of the studied alloy, and the hot deformation activation energy is 132.52 kJ/ mol. The average relative error between the predicted and experimental values is only 4.58%, and r(2) is as high as 0.988, indicating that there is good consistency between the experimental value and the predicted value. When the strain rate keeps unchanged, the elongation of the studied alloy shows an upward trend in the lower deformation temper-ature range (400-425 degrees C). When the deformation temperature continued to rise to 475 degrees C, the elongation of the studied alloy decreased sharply. Based on the analysis of fracture morphology, a large number of dimples can be observed at 450 degrees C/0.001s(-1), which is a typical ductile fracture. With increasing of deformation temperatures, the fracture mech-anism gradually changes from ductile fracture to brittle fracture. Under the condition of 425 degrees C/0.01s-1, there are a lot of dislocations in the alloy, and the dislocation walls are formed. With the increase of deformation temperatures or the decrease of strain rates, the dislocation density gradually decreases and dynamic recrystallization occurs. The soft -ening mechanism of the studied alloy changes from dynamic recovery to dynamic recrystallization. (c) 2023 Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

The hot tensile deformation behavior of 7075 aluminum alloy sheet was studied at deformation temperatures of 400-475 degrees C and strain rates of 0.001 to 1s(-1). Microstructure evolution and fracture morphology were observed. The hyperbolic sine Arrhenius constitutive equation can characterize the flow behavior of the alloy, and the hot deformation activation energy is 132.52 kJ/mol. The fracture mechanism changes from ductile to brittle with increasing deformation temperatures.