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作为挤压铸造中的一个重要参数,比压严重影响铸件的组织和性能。利用有限元法对凸式冲头挤压铸造进行了热力耦合数值模拟,分析了A356合金铸件比压与显微组织和力学性能的关系,得到了经济的临界比压。结果发现,随着比压增大,缩孔、缩松缺陷逐步减少,直至基本消失。进一步加大比压后,变化不明显,反而增加了模具的负担。随着比压增大,组织晶粒逐步细化,达到120MPa时,晶粒尺寸减小了8%,另外,二次枝晶间距缩小了12.5%,但当比压继续增大之后,没有出现继续细化,反而有粗化的趋势。
As an important parameter in squeeze casting, the specific pressure seriously affects the structure and properties of castings. The finite element method was used to simulate the heat transfer of the extrusion die for the convex punch. The relationship between the specific pressure, the microstructure and the mechanical properties of the A356 alloy castings was analyzed, and the critical critical pressure of the economy was obtained. The results showed that with the increase of specific pressure, shrinkage and shrinkage defects gradually decreased until they disappeared. Further increase the pressure, the change is not obvious, but increased the burden on the mold. With the increase of specific pressure, the grain size of the microstructure was gradually refined. At 120 MPa, the grain size decreased by 8%. In addition, the spacing of the secondary dendrites was reduced by 12.5%. However, when the specific pressure continued to increase, the grain size did not appear Continue to refine, but there is a trend of coarsening.