Hot Deformation Characteristic And Processing Maps Of 7059 Aluminum Alloy

In this paper, the as-cast super-high strength 7059 aluminum alloy was used as the research object. The deformation temperature is 330 ℃ 450 ℃, the strain rate of 0.01s^-110s^-1 and the deformation was 50 % under the conditions of isothermal simulation experiment tests. According to experimental results, the paper analyzes the true stress-strain curves under different deformation conditions. Based on the Arrhenius type hyperbolic sine equation established the constitutive equation of 7059 aluminum alloy by hot deformation and the validation. Metallographic microscope, scanning electron microscope and transmission electron microscope to analysis the microstructure of 7059 aluminum alloy under different deformation conditions. According to the theory of dynamic materials model, established the 7059 aluminum alloy hot processing maps and on the basis of analysis of the microstructure to determined the best hot deformation process.The experimental results show that the 7059 aluminum alloy with the increase of deformation temperature or the decrease of the strain rate the flow stress decreases. The material softening way from the dynamic recovery to dynamic recrystallization with the temperature increases. The established for the constitutive equation:ε=3.825*10¹⁶[sinh（0.01096σ）] ⁶⁶⁶exp（-224433 / RT）, Contrast in the peak stress under different deformation conditions calculated values and experimental values shows the error is smaller and the constitutive relation established can truly reflect the dynamic characteristics of this alloy.Microstructure analysis show that the deformation temperature, materials prone to the occurrence of dynamic recrystallization. At a lower temperature, the materials easily occurs dynamic recovery. As the strain rate increases, alloy dislocation density increases and the dynamic recrystallization is restricted, the materials easily occurs dynamic recovery. At a lower strain rate, the deformation time became longer, the dynamic recrystallization have occurred. Further proves that the material of microstructure with the decrease of the rise of temperature and strain rate by the dynamic recovery microstructure into dynamic recrystallization. From the hot processing map and combining with the characteristics of different regional microstructure in figure, determine the high dissipation rate of the alloy thermal deformation of machining region and difficulty in processing to the instability of area. Deformation conditions of instability of 10s^-1, 330 ℃⁴50 ℃ and the region that corresponds to the energy dissipation rate of less than 20 %. Tissue defect is local rheology. Processing region deformation condition of 450 ℃, 0.01s^-1 occur a complete dynamic recrystallization. The thermal deformation of 7059 aluminum alloy deformation condition is the best hot deformation process parameters.