【摘要】 采用正交试验法对厚度为4 mm的Al-Mg-Si系铝合金进行电子束焊，研究不同焊接工艺参数对接头显微组织与力学性能的影响。极差分析表明：影响接头抗拉强度的因素由大到小依次为焊接速度、电子束流、聚焦电流；方差分析表明：焊接速度和电子束流对接头抗拉强度的影响具有显著性，聚焦电流对接头抗拉强度的影响不显著。确定试验条件下的最佳工艺参数为：聚焦电流570 mA,电子束流25 mA,焊接速度16 mm/s,在该参数下获得接头的抗拉强度为212 MPa,达母材抗拉强度的65.8%。微观分析显示，接头焊缝区由柱状晶和等轴晶组成。焊缝区主要为α（Al）基体相，此外，还含有少量的Mg₂Si和Al₄CuMg₅Si₄强化相。接头区域的显微硬度测试表明：与母材区相比，熔合区的硬度有所降低。接头拉伸断口表面分布有数量较多的韧窝，呈明显的韧性断裂特征。更多还原

【Abstract】 Electron beam welding was carried out on the Al-Mg-Si aluminum alloy with the thickness of 4 mm by orthogonal experiment, and the effect of welding parameters on microstructure and mechanical properties of welded joint was investigated. The range analysis showed that the influence factors on joint tensile strength were ranked in turn: welding speed, electron beam current and focusing current. The analysis of variance showed that the welding speed and electron beam current had great effect on the tensile strength of welded joint, while that of the focusing current was not obvious. Under the experimental condition, the optimized welding parameters was determined as follows: focusing current was 570 m A, electron beam current was 25 m A, welding speed was 16 mm∕s. The tensile strength of joint by this welding procedure was 212 MPa, which was 65. 8% of that of the base metal. Microstructure analysis showed that the weld metal was composed of columnar crystals and equiaxed grains. There was mainly α( Al) matrix phase in weldment. Moreover, there also existed some strengthening phases such as Mg2Si and Al4Cu Mg5Si4. Measurement of microhardness in weld zone indicated that the hardness in fusion zone was decreased to a certain extent, compared with that of the base metal. There were many dimples on the tensile fracture surface of joint, and it obviously presented the characteristic of ductile fracture.更多还原