Effect Of Synergy Between Ultrasound Power And Solidification Pressure On The Microstructure Of Vacuum Counter-Pressure Casting Aluminum Alloy

Vacuum Counter-pressure Casting (VCPC) is a kind of advanced precision forming method of the anti-gravity in which the filling are at low counter-pressure and the solidification are at high pressure, it has good filling and solidification mechanical conditions, and has a huge advantage to produce the large complex thin-walled aluminum alloy castings, The power ultrasonic vibration has a big effect on the microstructure aluminum alloy. Through combining the characteristics and advantages of VCPC and power ultrasonic vibration, study on the effect of synergy between ultrasound power and solidification pressure on the microstructure of VCPC aluminum alloy, and to provide new ideas tor improve the quality of the large complex thin-walled aluminum alloy castings.Through introducing ultrasonic vibration device in the VCPC equipment, study on the effect of synergy between ultrasound power and solidification pressure on the microstructure of VCPC aluminum alloy, explore the laws of ultrasound power solidification pressure and their synergy on the microscopic morphology of VCPC ZL114A aluminum alloy casting and the secondary dendrite arm spacing(SDAS). The results show that ultrasound power and solidification pressure has a great influence on the microstructure of VCPC aluminum alloy casting in their synergy, and the solidification pressure play the leading role in the solidification process; But the influence of solidification pressure on the microstructure decreases with the increasing of the ultrasound power, When the best ultrasonic power is 600W, With the increase of the solidification pressure, the number of the microstructure to be changed into fine equiaxed grain and granular grain become more and more, and the microstructure and SDAS become more finer and uniform; Synergistic effect of ultrasound power and solidification pressure on the different specimen parts is different, aluminum alloy dendrite size and SDAS distance from the tool head begin to decrease and then increases, when the distance beyond the middle of the sample, they began gradually decreases; the paper establish a relationship between the SDAS and ultrasound power and solidification pressure, when the synergistic effect of ultrasound power and solidification pressure on VCPC 012mm aluminum alloy specimen: λSDAS=31.72-7.01×10-2 P1-6.96×10-3U+9.09×10-5 P1/2+5.21×10-6U2+1.04×10-6P1UEstablished the formulas of the total feeding driving force (F总) during solidification process while synergistic effects of ultrasound power and solidification pressure on the microstructure of VCPC aluminum alloy:With the increase of the total feeding driving force F总, the number of the microstructure to be changed into fine equiaxed grain and granular grain become more and more, and the microstructure become more finer and uniform. The results of the study provide a new way for produce the large complex thin-walled aluminum alloy parts, it will lay the theoretic and technical foundation for the future popularize synergistic effect of ultrasound power and solidification pressure on the microstructure of VCPC aluminum alloy.