(湖南大學(xué) 材料科學(xué)與工程學(xué)院，長(zhǎng)沙 410082)
摘 要: 采用CO2激光對(duì)軋制態(tài)ZK40鎂合金板材進(jìn)行焊接，并研究焊接工藝參數(shù)對(duì)接頭顯微組織及力學(xué)性能的影響規(guī)律。結(jié)果表明：在合理的工藝條件下，可以獲得成型良好的焊接接頭，其抗拉強(qiáng)度可達(dá)到315MPa，為母材的91.3%；熔池邊界無(wú)外延生長(zhǎng)的柱狀晶，整個(gè)熔池完全由細(xì)小均勻的等軸樹枝晶組成；分布于晶界及枝晶臂間的第二相粒子主要是Mg51Zn20；隨著焊接熱輸入的增大，枝晶臂生長(zhǎng)更為發(fā)達(dá)，晶粒粗化。
關(guān)鍵字: ZK40鎂合金；激光焊接；顯微組織；力學(xué)性能
（School of Materials Science and Engineering, Hunan University, Changsha 410082, China）
Abstract:The as-rolled ZK40 magnesium alloy sheets were joined by laser beam welding. The effects of welding parameters on the microstructures and mechanical properties of the joints were studied. The results show that a sound bead, with the ultimate tensile strength of 315 MPa, up to 91.3% of that of base metal, can be obtained with the optimized welding parameters. No columnar grains can be found at the fusion boundary, and the fusion zone (FZ) is characteristic of equiaxed dendritic grains and fine Mg51Zn20 precipitates disperse along the grain boundaries and among the dendritic arms. With the heat input increasing, the grains in FZ get coarser and more dendritic.
Key words: ZK40 magnesium alloy; laser beam welding; microstructure; mechanical property
