Effect Of Mechanical Vibration On The Microstructure And Mechanical Properties Of Aluminum Alloy Obtained By Expendable Pattern Shell Casting

At present, the demand for complex aluminum alloy precision casting is more and more high, and the performance requirements are higher and higher in the aerospace, automobile, electronics and military industries. Lost foam casting technology is a kind of precision casting method for producing complex aluminum alloy which is a combination of lost foam casting and investment casting. However, due to the disappearance of the mold shell mold casting use of dry sand molding, slow heat dissipation, making the casting grain size, mechanical properties. In this study, combined with the vanishing mould casting its own characteristics, by means of powder dry sand vibration compaction machine for aluminum alloy solidification process to improve the microstructure and properties of aluminum alloy, provide a economical and effective method. In this paper, the effects of the thickness of the specimen, the pouring temperature, vibration frequency and amplitude on the microstructure and properties of the cast aluminum alloy were studied.With the increase of the thickness of the sample, the grain size of the sample increases, the microstructure becomes larger, and the mechanical properties of the sample are decreased. When the mechanical vibration is applied, the grain size and morphology of the samples are more obvious, and the mechanical properties of the aluminum alloy are increased with the increase of the thickness of the specimen. The tensile strength, yield strength, elongation and hardness of Al alloy increased by 35%, 8.6%, 59.7% and 20.7% when the wall thickness is 40 mm. With the decrease of pouring temperature, the microstructure of Al alloy is refined. But the pouring temperature is too low to play the best effect, which makes the structure of the dendritic structure increased, and the grain size is no more obvious. At 730, the microstructure of the alloy is ideal, the primary phase is small, and the eutectic silicon is distributed on the grain boundary, and the mechanical properties of Al alloy are higher.With the increase of the vibration frequency, the aluminum alloy structure has been refined, and the mechanical properties of Al alloy have been improved. When the vibration frequency is 100 Hz, the microstructure refinement effect is the best, the grain size of the primary alpha phase is only 198.42 um, and the eutectic silicon is also basic to the fine grain size distribution, and the mechanical properties of the aluminum alloy are higher. The increase amplitude can significantly refine the microstructure of aluminum alloy, the larger the amplitude is, the more obvious the refinement effect is, the higher the mechanical properties of Al alloy. When the amplitude is increased to 1 mm, the grain size of the casting is the best, the shape of the alloy is rounded, and the mechanical properties of the alloy are higher.