线能量对挤压AZ91D镁合金GTAW焊接接头组织与性能的影响  

Effect of Line Energy on the Microstructure and Properties of GTAW Welded Hot Extruded AZ91D Magnesium Alloy Joints

作　　者：游国强[1,2] 王向杰[1] 齐冬亮 郭强[1] 龙思远[1,2] 

机构地区：[1]重庆大学材料科学与工程学院,重庆400045 [2]重庆大学国家镁合金材料工程技术研究中心,重庆400044

出　　处：《材料工程》2013年第10期57-63,70,共8页Journal of Materials Engineering

基　　金：国家自然科学青年基金(51105393);中央高校基本科研业务费项目(CDJXS11132226);重庆市科技攻关项目(CSTC2010AA4045);重庆大学大型仪器设备资助项目(2011121563)

摘　　要：通过显微组织观察、晶粒尺寸定量分析、显微硬度测试和拉伸实验等手段,系统研究了线能量变化对热挤压AZ91D镁合金钨极氩弧焊接接头微观组织、显微硬度和极限抗拉强度的影响。结果表明:线能量过低时,焊缝易出现未焊透和气孔缺陷,随着线能量的增加,熔合区和热影响区的晶粒尺寸均增大。线能量的增加导致热影响区和熔合区中的低熔共晶产物由连续状向颗粒状转变。适当的增加线能量有助于提高焊接接头平均显微硬度和极限抗拉强度,但过高的线能量会导致焊接接头的平均显微硬度和极限抗拉强度下降。这是因为当线能量增大到一定程度时,晶粒尺寸(霍尔-佩奇效应)、锌元素蒸发和过时效对金属材料强度产生的作用大于弥散强化(奥罗万强化机理)对材料强度产生的影响,霍尔-佩奇效应对材料性能的影响占主导地位。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 particu- late 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 re- sults 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.

关 键 词：AZ91D镁合金 钨极氩弧焊 显微组织 极限抗拉强度 

分 类 号：TG146.7[一般工业技术—材料科学与工程]