石膏型铸造铝合金真空增压凝固和真空自由凝固组织及力学性能

Study on Microstructures and Mechanical Properties of Plaster Mould Casting Aluminum Alloy Under the Condition of Vacuum Pressurizing Solidification and Vacuum Solidification

对比研究了真空增压凝固和真空自由凝固条件下ZL105A铝合金石膏型铸造凝固组织及其力学性能。结果表明,外加凝固压力不会影响实验合金凝固组织的相组成,但是能够细化α(A1)晶粒,使得二次相析出形态和分布更加均匀,并能够提高实验合金的补缩能力,减少缩松缺陷,增加组织致密度;同时,加压凝固可以提高石膏型铸造试验合金的抗拉强度和屈服强度,但对塑性的影响不明显。相同凝固条件下试验合金的拉伸强度和屈服强度随试棒尺寸增加呈下降趋势,而塑性略呈上升趋势。在真空增压凝固条件下,试验合金室温力学性能的尺寸效应显著增强。

Microstructures and mechanical properties of plaster mould casting aluminum alloy ZL105A under the condition of vacuum pressurizing solidification and vacuum solidification were studied. The results show that there is no effect on phase composition of solidification microstructures, the α（Al ） crystal grain was refined of sample solidified under pressure, the second phase distribution more homogenized, the feeding capacity and microstructures density were improved, the shrinkage porosity was decreased. Meanwhile, tensile strength and yield strength of the experimental alloy was improved, and there is no apparent effect on plastic property. Tensile strength and yield strength of the experimental alloy decreased with the increase of the size of specimen under the same condition, but plasticity was increased slightly. The size effect of mechanical properties for the experimental alloy was more obvious for the case under the condition of vacuum pressurizing solidification.