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通过设计不同宽度尺寸的缝隙浇道,借助FEM仿真计算分析与力学性能测试,研究了缝隙浇道宽度对A357铝合金铸件凝固组织与力学性能的影响。结果表明,受铸件/铸型界面传热影响,凝固固相从界面尖端换热区域析出分布,并逐渐转移至心部区域;缝隙浇道宽度与铸件壁厚比例系数设置偏低时,受缝隙浇道补缩影响,易产生集中性缩松缺陷;反之,受缝隙浇道截面临界压力与凝固末期反抽影响,易产生氧化夹渣与缩松缺陷。缝隙浇道宽度与铸件壁厚的最佳比例系数为1.2,此时A357合金的抗拉强度、屈服强度与伸长率分别为342 MPa、310 MPa与9.4%,断口形貌为韧窝断裂。
Through the design of slot gate with different width and width, the effect of slot width on solidification microstructure and mechanical properties of A357 aluminum alloy castings was studied by means of FEM simulation analysis and mechanics performance test. The results show that, due to the influence of heat transfer on the interface between the casting and the mold, the solidified solid phase is precipitated from the heat exchange zone at the tip of the interface and gradually transferred to the core area. When the ratio of the width of the slot gate to the wall thickness of the casting is set low, Runner fill shrinkage, easy to produce concentrated shrinkage defects; the other hand, by the gate runner section critical pressure and the end of the solidification of the anti-pumping effect, easy to produce oxide slag and shrinkage defects. The optimal ratio coefficient of slot gate width and casting wall thickness is 1.2. At this time, the tensile strength, yield strength and elongation of A357 alloy are 342 MPa, 310 MPa and 9.4%, respectively. The fracture morphology is dimple fracture.