Effect Of Ultrasonic Vibration Temperature On The Microstructure And Mechanical Properties Of Vacuum Counter-pressure Casting Aluminum Alloy

Ultrasonic treatment is a kind of high efficiency and no pollution of fine grain physical solidification, as a result, solidification microstructure can be refined. Vacuum counter-pressure casting is a new kind of casting process, adopting the process principles of vacuum filling mould under low pressure and melts crystallizing under high pressure, the combination of ultrasonic melt treatment technology and vacuum counter-pressure casting technology would provide a new idea for the production of large thin wall complex precision castings. However, ultrasonic vibration temperature is an important parameter to obtain excellent microstructure and properties in the synergic process of ultrasonic vibration and vacuum counter-pressure casting. Therefore, the effect of ultrasonic vibration temperature on the microstructure and mechanical properties of the vacuum counter-pressure casting aluminum alloy was studied, provided theoretical basis and technical support for the application of ultrasonic vibration and vacuum counter-pressure coordination field.It takes the ZL114 A alloy as the research object in this paper, on the basis of studying the ultrasonic vibration temperature and pouring temperature on microstructure and mechanical properties of gravity casting and vacuum counter-pressure casting aluminum alloy respectively. The laws and mechanism of ultrasonic vibration temperature on the microstructure and mechanical properties of aluminum alloy under ultrasonic vibration and vacuum counter-pressure coordination field were studied further. The results indicate that the effect of ultrasonic vibration temperature on the microstructure and mechanical properties of ZL114 A alloy was significantly affected under ultrasonic vibration and vacuum counter-pressure coordination field, the optimum ultrasonic vibration temperature is 700℃ in the gravity casting, and the best pouring temperature is 700℃ in the vacuum counter- pressure casting. Meanwhile, the primary phase and eutectic silicon morphology of samples were changed significantly and the density, tensile strength and elongation of samples increase first and then decrease with the increase of ultrasonic vibration temperature in the synergic process of ultrasonic vibration and vacuum counter-pressure casting, all of them reach the best when the ultrasonic vibration temperature is 720℃, as a result, the primary phase and eutectic silicon morphology of samples have been obviously refined, the density, tensile strength and elongation of samples reach the maximum value, which are 0.9998, 326.96 Mpa and 5.57% respectively. the density, tensile strength and elongation of samples are increase by 0.41%, 13.23% and 20.56% respectively compared with ultrasonic gravity casting ZL114 A alloy at the same part, and they are increase by 0.12%, 3.82% and 3.53% respectively compared with vacuum counter-pressure casting ZL114 A alloy. The cleavage planes and cleavage steps of fracture morphology were significantly reduced, And there are a large number of uniformly distributed and regularly shaped dimples, compared with the former two methods, the shape of dimple is more rounder and smaller.Therefore, the optimum ultrasonic vibration temperature is beneficial to obtain excellent microstructure and properties under ultrasonic vibration and vacuum counter-pressure coordination field. The research results have laid a theoretical and technical basis for the production of complex thin wall aluminum alloy castings in the synergic process of ultrasonic vibration and vacuum counter-pressure casting, which has important theoretical and practical significance.