搅拌摩擦加工铸态AZ31镁合金组织与性能研究

Microstructure and Properties of Friction Stir Processed Cast AZ31 Magnesium Alloy

摘要:

采用搅拌摩擦加工技术对铸态AZ31镁合金进行单道次加工，研究加工区域的微观组织和力学性能。结果表明：搅拌摩擦加工过程中，材料发生了剧烈的塑性变形，粗大的β-Mg17Al12相显著破碎，形成细小、均匀的再结晶组织。XRD分析表明，搅拌摩擦加工导致大量的β相固溶到镁合金基体中，产生固溶强化作用。搅拌摩擦加工后的试样平均HV硬度值为810 MPa，高于铸态AZ31镁合金的硬度值，抗拉强度比铸态AZ31镁合金提高43 MPa，延伸率提高4.3%，拉伸断口表现为微孔聚合剪切断裂特征。

Abstract:

The cast AZ31 magnesium alloys were treated by a single-pass friction stir processing (FSP), and the microstructure and mechanical properties of the processed region were studied. The results show that severe plastic deformation occurs and the coarse eutectic β-Mg17Al12 phase was broken, forming a refined and homogeneous dynamic recrystallized microstructure during the FSP period. XRD patterns indicate that a large amount of β phase dissolve into the magnesium matrix because of FSP, resulting in solid solution strengthening. The average microhardness (HV) of the FSPed AZ31 sample is 810 MPa higher than that of the cast AZ31 alloy, and the ultimate tensile strength and elongation of FSPed sample increase by 43 MPa and by 4.3% compared with those of the cast AZ31 alloy, respectively. Moreover, the fracture surface of FSPed AZ31 sample exhibits a typical ductile dimple-fracture.