Microstructure evolution and constitutive equation of wire arc additive manufactured 2219 aluminum alloy during hot deformation
The hot deformation behavior of wire arc additive manufactured(WAAM)2219 aluminum alloy was studied by hot compres-sion method,and the deformation temperature was 360-510℃,the strain rate was 0.01-10 s-1.The effects of temperature and strain rate on the flow stress and microstructure were analyzed.The hot deformation constitutive equation of WAAM 2219 aluminum alloy was es-tablished with hyperbolic sinusoid function of Zener-Hollomon parameter.The results show that the hot compression peak stress of WAAM 2219 aluminum alloy decreases gradually with the increase of temperature and the decrease of strain rate.For WAAM alloy,only sliding deformation occurs at 420℃and below,and dynamic recrystallization occurs at 450℃and above.480℃is the best forging temperature and complete dynamic recrystallization occurs,which can effectively refine the additive grains.The constitutive equation is divided into two stages taking the dynamic recrystallization temperature(450℃)as the critical point.The deformation activation energy is 212.53 kJ·mol-1 below the dynamic recrystallization temperature and 163.37 kJ·mol-1 above the dynamic recrystallization temperature.The eu-tectic θ phases distributed along the grain boundaries broke and are solid dissolved in the process of hot compression.The higher the de-formation temperature is or the small the strain rate is,the higher the solid solution degree is.
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