A356铝合金挤压铸造凝固过程及热处理对其性能的影响  

Solidification Process of Squeeze Casting and Effect of Heat Treatment on Properties of A356 Aluminum Alloy

作　　者：邱谨[1] 曹杨婧 罗晓梅[1] 周宏伟[1,2] 曹驰 毕广利[1,2] 李元东[1,2] Qiu Jin;Cao Yangjing;Luo Xiaomei;Zhou Hongwei;Cao Chi;Bi Guangli;Li Yuandong(State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals,Lanzhou University of Technology,Lanzhou 730050;Key Laboratory of Nonferrous Metal Alloys and Processing,Ministry of Education,Lanzhou University of Technology,Lanzhou 730050;Wenzhou Pump and Valve Engineering Research Institute of Lanzhou University of Technology,Wenzhou 325102)

机构地区：[1]兰州理工大学省部共建有色金属先进加工与再利用国家重点实验室,兰州730050 [2]兰州理工大学有色金属合金及加工教育部重点实验室,兰州730050 [3]兰州理工大学温州泵阀工程研究院,温州325102

出　　处：《特种铸造及有色合金》2024年第2期189-197,共9页Special Casting & Nonferrous Alloys

基　　金：甘肃省自然科学基金资助项目(22JR5RA251)。

摘　　要：采用数值模拟和金相组织分析研究了A356铝合金挤压铸造成形顺序及凝固过程,发现半固态挤压铸造不仅充形平稳,凝固时间短,且孔隙率低。通过固溶、时效热处理可以改善金属型铸造、液态挤压铸造、半固态挤压铸造试样的组织及性能。结果表明,固溶处理后α-Al基体晶粒形貌与铸态相同,晶粒尺寸稍有长大,共晶Si球化尺寸集中在1.5μm左右。随着固溶温度升高,力学性能与热导率先增加后减小,而半固态挤压铸造后合金力学性能在560℃下固溶时并未降低。进一步时效处理后,过饱和的固溶体中析出弥散分布的Mg_(2)Si强化相,其不仅能够阻碍位错运动,提高A356铝合金的抗拉强度,而且减少了固溶原子与空位对电子的散射作用,提高导热性能。540℃×4 h固溶+180℃×9 h时效处理后,半固态挤压铸造试样性能最佳,其抗拉强度、伸长率、热导率分别为283.65 MPa、13.2%、191.82 W/(m·K)。The numerical simulation and microstructure analysis were applied to understand the forming sequence and solidification process of squeeze casting A356 aluminum alloy.The results indicate that semi-solid squeeze casting exhibits stable filling,short solidification time with low porosity.The microstructure and properties of the alloy by metal mold casting,liquid squeeze casting and semi-solid squeeze casting can be improved after solution and aging heat treatment.The results reveal that the grain morphology of α-Al matrix is the same as that of as-cast ones and the size is slightly larger,and the eutectic silicon is spheroidized and the size is around 1.5μm after solution treatment.The mechanical properties and thermal conductivity of the alloy are increased at first and then decreased with the increase of solution temperature,while the mechanical properties of semi-solid squeeze casting keeps stable in the solution tem perature range of 560℃.After further aging treatment,dispersed Mg_(2)Si strengthening phase can be precipitated from the supersaturated solid solution,which can not only improve the tensile strength of A356 aluminum alloy by hindering dislocation movement,but also improve the thermal conductivity by reducing the scattering effect of solid solution atoms and vacancies on electrons.The semi-solid squeeze casting specimen exhibits the satisfied performance after solution treatment at 540℃ for 4 h and aged treatment at 180℃ for 9 h,where the tensile strength,elongation and thermal conductivity reach 283.65 MPa,13.2% and 191.82 W/(m·K),respectively.

关 键 词：挤压铸造 半固态 数值模拟 热处理 热导率 

分 类 号：TG146.21[一般工业技术—材料科学与工程] TG249.9[金属学及工艺—金属材料]