摘要
在镁合金(AZ91D)TIG焊接头中,同质焊缝的相组成主要为α-Mg和β-Al12Mg17;β-Al12Mg17非连续地分布于α-Mg的晶界;β-Al12Mg17的体积分数为7.3%。焊接热影响区(特别是近缝区)最突出的显微组织特点是晶粒粗化和连续分布于晶界的β-Al12Mg17金属间化合物。由于晶粒细化焊缝区硬度值高于母材,而热影响区的硬度值则明显低于母材。与母材相比(σb=156 MPa,δ=4.8%),同质焊缝金属有更高的力学性能(σb=192 MPa,δ=4.9%)。焊接接头的力学性能明显低于母材,接头强度为母材强度的69%;接头塑性为母材的72%;断裂主要发生在热影响区的近缝区。降低焊接热输入有利于改善焊接接头的力学性能。
On the TIG welded magnesium alloy AZ91D joints, the weld seam was composed of α- Mg and β- Al12 Mg17, which discontinuously distributed on the a - Mg grain boundaries and the volume fraction of β - Al12Mg17 was 7.3%. The most explicit microstructure features of the heat affected zone （HAZ） were grain coarsening and continuous intermetaUic compound β - Al12 Mg17 on the grain boundaries. The hardness of the weld seam was higher than that of the base metal and the HAZ had the lowest hardness value on the joint. The weld seam had the superior mechanical properties （ σh= 192 MPa,δ = 4.9% ） compared with the base metal （ σh = 156 MPa, δ = 4.8% ）. The strength and plasticity of the welded joint were respectively 69% and 72% that of the base metal. Fracture mainly occurred on the HAZ adjacent to the fusion line and decreasing the heat input was helpful to improve the mechanical properties of the welded joint.
出处
《焊接》
北大核心
2006年第1期35-38,共4页
Welding & Joining
关键词
镁合金
TIG焊
显微组织
力学性能
magnesium alloy, TIG welding, microstructure, mechanical properties
