真空水平连铸AZ31镁合金的显微组织与性能

Microstructure and Properties of Vacuum Horizontal Continuous Casting AZ31 Magnesium Alloys

在真空条件下用石墨水冷铜模复合铸型连续制备出直径为10mm的AZ31镁合金棒材。并与金属型铸造法获得的母合金试样对比,分析了AZ31镁合金棒材的显微组织及力学性能。结果表明,真空水平连续铸造的AZ31镁合金的显微组织由细小均匀的等轴晶组成,其平均晶粒尺寸由300μm减小到35μm,因此合金具有良好的综合力学性能,抗拉强度及伸长率分别提高了37.6%及112.5%。试样的拉伸试验断口中解理小刻面减少并缩小,河流状花样由撕裂棱相互连接,且韧窝的数量明显增多,呈准解理断裂的特征。

AZ31 magnesium alloy bars with φ10 mm in diameters were prepared by vacuum horizontal continuous casting （VHCC） with a multi-mold composed of heated graphite mold and water cooling copper mold. Through comparing with master magnesium alloys prepared by metal mold casting, the micro- structure and mechanical properties of the AZ31 bars prepared were investigated. The results show that the microstructure of VHCC AZ31 magnesium alloy consists of fine equiaxed grains with the size reduced from 300 μm to 35 μm, therefore the alloy prepared exhibits desirable comprehensive mechanical properties. The tensile strength and elongation are increased by 37.6% and by 112.5%, respectively. The tensile fractures of the AZ31 magnesium alloy, in which cleavage facets become fewer and smaller while dimples and tear edges connecting together into river-like patterns become more, apparently presenting characteristics of quasi cleavage.