Effect of Line Energy on the Microstructure and Properties of GTAW Welded Hot Extruded AZ91D Magnesium Alloy Joints
YOU Guo-qiang1,2, WANG Xiang-jie1, QI Dong-liang1, GUO Qiang1, LONG Si-yuan1,2
1. College of Materials Science and Engineering, Chongqing University, Chongqing 400045, China;
2. National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044, China
Abstract：The influence of line energy on the microstructures, microhardness and ultimate tensile strength (UTS) of gas tungsten arc welded (GTAW) hot extruded AZ91D magnesium alloy plates were investigated by microstructural observations, quantitative analysis of grain size, microhardness tests and tensile tests. The results show that the weld prone to emerge defects such as incomplete penetration and porosity if the line energy is too low, and the grains both in the fusion zone (FZ) and the heat-affected zone (HAZ) increased with an increase of the line energy. Moreover, an increase of the line energy result in transition of low melting eutectic products from continuous shape to particulate shape in both the FZ and the HAZ. The microhardness and ultimate tensile strength (UTS) of the welded joint increased with an increase of the heat input, however, an over high line energy results in a decrease both for the microhardness and the ultimate tensile strength of the welded joint. When the line energy increases to a certain amount, the effects of grain size (Hall-Page effect), evaporation of zinc and over aging on the properties of metallic materials are greater than that of dispersion strengthened (Orowan strengthening mechanism), and the H-P effect is of the dominant on the material properties.
游国强, 王向杰, 齐冬亮, 郭强, 龙思远. 线能量对挤压AZ91D镁合金GTAW焊接接头组织与性能的影响[J]. 材料工程, 2013, 0(10): 57-63,70.
YOU Guo-qiang, WANG Xiang-jie, QI Dong-liang, GUO Qiang, LONG Si-yuan. Effect of Line Energy on the Microstructure and Properties of GTAW Welded Hot Extruded AZ91D Magnesium Alloy Joints. Journal of Materials Engineering, 2013, 0(10): 57-63,70.
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