Dual Head Power Ultrasonic Vibration Treatment Of A356Semi-solid Slurry Organizationand Its Mechanism

Semi-solid metal forming technology is a metal processing technology in the21stcentury cutting-edge, has being more wide attention in the industry worldwide, andobtain uniform and fine spherical primary crystals organization has been pursued bymany researchers work objectives. Currently, the methods of preparation semi-solidslurry have much variety, domestic and foreign researchers have also made theirdifferent pulping methods. Indirect method of power ultrasound, in which itsnon-polluting, high efficiency and simple process to become a new type of advancedenvironmental technologies, but also become the focus of the study.We have invented a set of funnel-type of power ultrasonic double vibrating headequipment to prepare semi-solid A356alloy slurry and study the impact of the law ofthe relevant process parameters on the microstructure of semi-solid. Funnel-type ofpower ultrasonic double vibrating head equipment for the preparation of semi-solidA356alloy melt organization has a clear role in the refinement and ball. When thefunnel angle is45°, the optimum casting temperature is610℃. When the castingtemperature is610℃, the microstructure of the edge for the slurry in the waterquenching after the primary topography is preferably α–Al, the grain size is29μm, thedistributed is most evenly, the ball effect is also the most obvious, the average shapefactor is0.84. When the casting temperature is620℃, after the water quenching, thesemi-solid slurry of aluminum alloy A356to the center grain size of the microstructureof primary α–Al is32μm, the average shape factor is0.78.And the temperaturedifference between the center and the edge of the organization is about10℃. Underthe same pouring temperature, the flow path of the semi-solid material condensateslurry of A356aluminum alloy microstructure newborn α-Al morphology and grain sizemostly ranged, which is between the edge and the center of the microstructure after thewater quenching.According to the experimental results that the ultrasonic vibrating device treat thesemi-solid slurry, and obtained clearly grain refinement, investigate the ultrasoundeffect on the crystallization process of the semi-solid melt. In heterogeneous nucleationprocess, the thermal effects provide greater energy of ups and downs, the mechanicaleffect provides greater structure of ups and downs, thus contributing to theheterogeneous nucleation rate increases, the mechanical effects and the acoustic streaming effects caused more remarkable than the thermal effects. The power of liquidcrystal blanks particle movement not only from thermal fluctuations, but also from theultrasound effects in the role of mechanical effect of directional reunion. The greatestimpact of ultrasound effect is the cellular dendrite growth, which between positive andnegative temperature gradient, the acoustic streaming effect have change the forefrontof the melt crystallization temperature field and accelerate cellular grain refinement,eventually forming globular organization. The rate of crystal growth is accelerated bythe special influence of ultrasonic wave, so the acoustic streaming of stirring effect havegreater impact.