7075铝合金半固态浆料制备及流变压铸工艺研究

Preparation and Rheological Die-Casting of 7075 Aluminum Alloy Semisolid Slurry

目的研究搅拌速度和搅拌时间对ACSR工艺制备的7075铝合金半固态浆料组织的影响,研究和比较传统压铸与流变压铸7075铝合金的组织与性能。方法通过改变搅拌速度和搅拌时间制备7075铝合金半固态浆料,取料水淬获得半固态坯料,将剩余浆料进行流变压铸,采用金相显微镜、扫描电子显微镜、万能试验机等研究了试样的微观组织、拉伸性能与断口形貌,探究搅拌速度和搅拌时间对7075合金半固态浆料组织的影响,同时研究与比较传统压铸与流变压铸7075铝合金的组织性能。结果在一定范围内提高搅拌速度和搅拌时间有利于α1-Al的细化与球化,与传统压铸7075铝合金相比,流变压铸合金具有更优异的力学性能,T6热处理后,其抗拉强度、屈服强度和伸长率分别为547 MPa、494 MPa和3.2%。结论 ACSR工艺可制备出组织细小圆整的7075铝合金半固态浆料,且流变压铸可改善7075铝合金力学性能。

The paper aims to study the effects of stirring speed and stirring time on the microstructure of 7075 aluminum alloy semisolid slurry prepared by ACSR process, and to study and compare the microstructures and properties of 7075 alloy prepared by traditional die-casting and rheological die-casting processes. In this paper, the semisolid slurry of 7075 aluminum alloy was prepared by altering the stirring speed and stirring time. Part of the semisolid slurry was taken out for water quenching to obtain the semisolid billets. The remaining semisolid slurry was poured into the chamber of die-casting machine for rheological die-casting. Microstructures, tensile properties and fracture morphology of the samples were studied by means of metallographic microscopy, scanning electron microscope and universal testing machine. The effects of stirring speed and stirring time on the microstructure of 7075 aluminum alloy semisolid slurry were investigated. The microstructure and mechanical properties of 7075 aluminum alloy by traditional die-casting and rheological die-casting processes were also studied and compared. The results indicated that increasing the stirring speed and stirring time in a certain range was beneficial to the refinement and spheroidization of α1-Al grains. Compared with 7075 aluminum alloy by traditional die-casting process, the alloy by rheological die-casting process had better mechanical properties. After T6 heat treatment, its tensile strength, yield strength and elongation were 547 MPa, 494 MPa and 3.2% respectively. The semisolid slurry of 7075 aluminum alloy with fine and spherical microstructure can be prepared by the ACSR process, and the mechanical properties of 7075 aluminum alloy can be improved by rheological die-casting.