熔体超声处理对A356合金铸态显微组织和力学性能的影响

Effect of Melt Ultrasonic Treatment on Microstructure and Mechanical Properties of As-cast A356 Alloy

采用高能超声装置对A356合金熔体进行处理,利用扫描电镜、万能材料试验机等研究了高能超声功率及处理时间对A356合金铸态显微组织和力学性能的影响,并分析了其作用机理。结果表明:对A356合金熔体进行超声处理后合金铸态组织中的硅相逐渐由树枝状变成颗粒状,-αAl相细小圆整;当超声功率为1.2 kW、处理时间为600 s时,处理效果最好;处理时间一定后,随着超声功率的提高,A356合金的抗拉强度、屈服强度和伸长率都增加,最大值可分别达到294.37,207.98 MPa和6.85%,分别为未施加高能超声处理的1.56,1.93和1.10倍;随着高能超声处理时间的延长,A356合金的抗拉强度、屈服强度以及伸长率呈现先升后降的趋势。

High energy ultrasonic instrument was used to prepare as-cast A356 alloy. The effect of highenergy ultrasonic on the microstructure and mechanical properties of A356 alloy was investigated by means of SEM and universal testing machine. The mechanism was analyzed. The results indicate that the morphology and sizes of the α-Al and Si phases were obviously improved after ultrasonic treatment, the Si phase with long dendritic-shape was refined, and α-Al phase was refined and circled. The best ultrasonic effects were obtained with 1.2 kW power and 600 s applying time. When the applying time was fixed, the values of the tensile strength, yield stress and elongation of the A356 alloy increased with the increasing ultrasonic power, the maximums could reach 294. 37, 207. 98 MPa and 6. 85%, respectively, which were 1.56, 1.93 and 1. 10 times to that of the alloy without high-energy ultrasonic treating. With the increasing applying time, the tensile strength, yield stress and elongation of the A356 alloy increased first, and then decreased.