电磁搅拌对压铸镁合金组织性能的影响

对5mm厚的压铸镁合金AZ91镁板进行电弧重熔过程中,外加纵向交流磁场。通过对重熔后试件进行力学性能和显微组织分析,研究磁场参数对AZ91组织和性能的影响规律,并对磁场作用机理进行研究。试验结果表明,外加纵向磁场通过旋转电弧对熔池进行搅拌,改变晶粒结晶过程,使重熔层中晶粒组织得到细化,进而使抗拉强度和硬度等性能得到改善,同时磁场的电磁搅拌作用可以净化液态镁合金(使杂质球化并弥散分布),促进气泡上浮,降低镁合金热裂纹敏感性,抑制热裂纹产生。

Effect of Electromagetic Stirring on Microstructure and Mechanical Properties of Die Casting Magnesium Alloy

AC longitudinal magnetic field was employed during remelting a 5 mm thick die casting AZ91 magnesium alloy plate with GTAW. The effect of magnetic field parameters on properties and microstructure of remelted AZ91 was studied throungh analyzing the tensile strength,hardness and microstruture. The action mechanism of magnetic field was explored. The results indicated that stirring on the molten pool by the AC lognitudinal magnetic field,can change the crystallization process,refine the crystal grains of remelted zone,so the tensile strength and hardness are also improved. At the same time,the molten pool can be purified by the eletromagnetic stirring,so the gas cavity and sensitivity of hot crack were decreased,and the formation of hot crack was restrained.