Ultrasonic Melt Treatment And Solidification Of 7055 Aluminum Alloy

It's an advanced technology for the introduction of outfield in the fabrication and processing of materials to control the processing and the structure of the materials. This paper investigated the effects of ultrasonic treatment of melt and ultrasonic solidification on Al-Zn-Mg-Cu series ultrahigh strength aluminum alloys, Both the macro- and micro-structure of the cast ingots were analyzed, their mechanical properties were studied to discuss the effects and mechanisms of the ultrasonic treatment.Ultrasonic treatment during solidification of 7055 aluminum alloy results in dendrite-free grain structure and leads to the fining of grain structure. The structure of the cast ingots presents the character of semisolid solidification.Ultrasonic treatment of the 7055 aluminum alloy melt before gravity casting fined the grain structure in the cast at the temperature range from 630℃ to 710℃. Compared to the cast ingots without ultrasonic melt treatment, hardness of homogenized as-cast alloy increases by 10% and its elongation increases from 3.8% to 7.7%, meanwhile its electric conductivity and tensile strength improves respectively.The study on ultrasonic melt treatment of the 7055 aluminum alloy followed by semi-continuous casting confirms that ultrasonic melt treatment could uniform the cast structure, and reduce the defects in the cast, especially suppresses the cracking, meanwhile improves the electric conductivity, tensile strength and elongation.By designing a water-cooled vibrator and applying it in the ultrasonic melt treatment of the 7055 aluminum alloys, the corrosion of the vibrator was eliminated. The structure of the 7055 aluminum alloy cast becomes more uniform. The hardness, electric conductivity and elongation of the cast are higher than the cast which melt is treated with no water-cooled vibrator.