基于组织特征的挤压铸造A356合金局部力学性能研究

Study on Local Mechanical Properties of Squeezing Casting A356 Alloy Based on Microstructural Characteristics

采用基于微观组织特征的有限元分析(FEA),计算了A356挤压铸件不同部位的力学性能。通过不同分析域尺寸、网格尺寸和FEA模型的分析,确定了合适的有限元模型,使用试验拉伸结果对FEA结果进行了验证,探讨了组织特征对性能的影响。结果表明,Si粒子长度和形状因子增大,抗拉强度与伸长率均呈下降趋势;Si粒子的密度和面积分数的增大,抗拉强度提高和伸长率降低;A356合金的损伤演化过程可分为Si粒子断裂(微裂纹的形成)、裂纹的扩展和连接三个阶段;Si粒子小而圆整且分布较均匀时,局部力学性能各向异性小,Si粒子长宽比较大且呈现出明显的方向性时,局部力学性能各向异性加大。

The local mechanical properties of A356 squeezing castings were studied by finite element analysis(FEA)with microstructure-based models.By analyzing different analysis domain sizes,mesh sizes and FEA models,the FEA models for each position were determined.Subsequently,the accuracy of the calculation results was validated by experimental results.Furthermore,the effect of microstructural characteristics on mechanical properties was explored,indicating that with an increase in Si particle length and shape factor,both the ultimate tensile strength and elongation exhibited a decreasing trend.Conversely,higher Si particle density and area fraction resulted in increasing ultimate tensile strength but decreasing elongation.The damage evolution process of the A356 alloy consisted of three stages:particle cracking(microcrack formation),crack propagation and connection.When the Si particles were small and uniformly distributed,the local mechanical properties exhibited low anisotropy.Conversely,when the Si particles had a larger aspect ratio and exhibited pronounced orientation,increased anisotropy was observed.