Study On Squeeze Casting Process Of 7075 Aluminum Alloy Hollow Axle Body Of Transmission Shaft

As an important parts of train bogie, transmission hollow shaft prepared by subsitituing low density aluminum alloy for steel, can reduce the weight of unsprung, improve transmission performance and promote the development of high-speed train. We examined ultra-high strength 7075 aluminum alloy,using squeeze casting method to prepare hollow shaft of reduction ratio, in order to provide reference for the development of aluminum alloy hollow shaft.The process parameters(squeeze casting pressure, pouring temperature, molding temperature) of squeeze casting and effects of heat treatment process were studied. The results are summarized below:(1) With the increase of casting pressure,microstructure of the samples become much finer. Microstructure under different pressures contained dendritic, granular and rose-shaped structure.solidification under prussure also reduce porosity, rarefaction and so on.(2) Low pouring temperature results in defects of misrun on the surface of casting, while high pouring temperature coarsen the microstructure. Low or high pouring temperature were both reduce density and mechanical property of the samples. The optimum pouring temperature range was about 680℃~700℃. A higher molding temperature also coarsen microstructure and reduce mechanical property of the samples. Experimental results indicates that the appropriate temperature of casting mold was around 250℃.(3) Under the experimental conditions, when casting pressure is 160MPa, the melt temperature is 700℃and mold temperature is 250℃, tensile strength and elongation of aluminum alloy hollow shaft specimen after heat treatment can reach to 545MPa and 8%, respectively.