Thixotropic Of A356 Aluminum Alloy Wheel Hub Forging Process And Organizational Performance Research

This study aimed at developing a simple-prepared, low-cost way to manufacturing A356Semi-solid aluminum Alloy billets, researching the reheating process of Semi-solid aluminum alloy billets and the transformation of microstructure in the reheating process. Then design the die of semi-solid die forging and discuss theory and technology of Semi-solid die forging, and contrast with melted metal squeezing. Finally optimized T6heat treatment technology of semi-solid die forging A356aluminum alloy wheel by orthogonal experiment.Beyond the analysis of advantages and disadvantages of the low superheat pouring and adding grain refiner method, this paper puts forward of the compound process of low superheat pouring and grain refining, this technology has the advantages of simple processing, no need of special equipment, low cost. The effect of the pouring temperature and the addition of chemical grain refiners on the microstructure of A356aluminum alloy has been investigated, and the optimum casting parameters are pouring temperature of635℃and grain refiner addition amount of0.2%.As a result, A356Semi-solid billets of spherical grain with average grain size of about40μm could be manufactured.The effect of reheating temperature and reheating time on the microstructure of A356aluminum alloy has been investigated in the reheating process, and both of transformation and mechanism were also discussed. This process included three stages:Homogenization of solid phase, liquid phase increase, growth and spheroidization of a-Al grain. The result showed that optimum reheating technology of A356aluminum alloy billets is reheating at600℃last for60minutes.Die forging included designing the die, Investigating the effect of reheating temperature and forging pressure on the microstructure and mechanical properties, optimizing die forging parameters, comparison with melted metal squeezing. Semi-solid die forging in improvement of surface quality, dimensional accuracy and density of internal tissue was superior to melted metal squeezing.Orthogonal experiment results showed that optimized T6heat treatment technology was solution treatment at535℃, last for2hours, then aging treatment at200℃,last for4hours. When reheating temperature at595℃, forging pressure is100T, tensile strength, yield strength and elongation of wheel hub that after T6heat treatment were332MPa,283MPa and11.8%,which were increased by18.9%,19.9%and35.6%compared with those manufactured by melted metal squeezing.