6061 aluminum alloy wheel hub was prepared by liquid die forging, and its structure is shown in Fig. 1. Samples were taken from different parts of the wheel hub by wire cutting method for microstructure observation and mechanical property test. The schematic diagram of sampling position of aluminum alloy wheel hub is shown in Fig. 2, and the size of tensile sample is shown in Fig. 3 (unit: mm) The microstructure of 6061 aluminum alloy was observed by axiovert 40mat metallographic microscope. The tensile strength and elongation of 6061 aluminum alloy were tested by WE-30 tensile testing machine
The inner rim, outer rim, rim and spoke of 6061 aluminum alloy wheel hub prepared by liquid die forging were sampled and observed. The results are shown in Fig. 4. It can be seen from Fig. 4 that the microstructure of different parts of the wheel hub is obviously different, and the grain size is also different It can be seen from 4A that the grain size of 6061 aluminum alloy wheel rim is the smallest, the microstructure is the most uniform and equiaxed, and there is a small amount of black second phase precipitate on the grain boundary 4b it can be seen that the grains in the inner rim of 6061 aluminum alloy wheel hub are fine and uniform, and most of them are equiaxed grains. The number of second phases on the grain boundary is more than that at the outer rim 4C, the grain size of 6061 aluminum alloy wheel hub is the coarsest and the structure is uneven. At the same time, the number of second phase on the grain boundary is also large, and there are large amount of second phase precipitates in local grain boundary area It can be seen from 4D that the grain size of 6061 aluminum alloy wheel rim is uneven, and the grains in local area are relatively fine, but there are also a few coarse grain areas. Some grains are elongated and deformed, and there are more precipitates on the grain boundary. 6061 aluminum alloy is Al Si mg aluminum alloy, and Mg2Si is the reinforcement phase of aluminum alloy During gold solidification, Mg2Si phase precipitates simultaneously in the grain boundary and grain boundary. Since the grain boundary is the final solidification site, there are more low melting point phases, so it is easy to form eutectic structure with Mg2Si phase.
