摘要本论文开展了7A52铝合金的激光+MIG复合焊接工艺研究，采用ER5356铝镁焊丝，研究了不同工艺参数对焊缝成形、组织及性能的影响，优化了工艺规范，获得了成形良好的焊缝。研究表明，随激光功率增大，焊缝成形越好，且在本试验参数范围内，激光功率对焊缝熔深、熔宽的影响不显著；在改变焊接速度、MIG焊接电流和离焦量等参数条件下，均得到了相应的能获得成形良好的焊缝的工艺规范。对微观组织的观察表明，焊缝区包含组织不同的两部分，从焊缝顶部至底部依次为含填充材料焊缝和母材自熔焊缝；组织图片表明热影响区很窄。采用不同激光功率时焊缝获得的最大抗拉强度为325MPa，达到母材抗拉强度的79%，断裂均发生于熔合区靠焊缝侧，即对应于硬度试验中表现出来的硬度最低处。67688

毕业论文关键词  7A52铝合金  激光+MIG复合焊接  焊缝  显微组织  力学性能

毕业设计说明书（论文）外文摘要

Title   Process study on laser + MIG hybrid welding of aluminum alloys 

Abstract

Laser + metal inert gas (MIG) hybrid welding of 7A52 aluminum alloys was studied with ER5356 wires. The effect of the main operating parameters on the quality of the bead, including its appearance, microstructure characteristics and mechanical properties were investigated. Under the optimal welding parameters, the sound beads were obtained. The results show that appearance of bead could be improved by increasing laser power, and within the parameter scope of this experiment, laser power had little influence on the weld penetration and weld width; process specifications of achieving good appearance of beads were obtained in test groups of changing welding speed, arc current, and defocusing distance respectively. Two different microstructures were included in weld zone named welding layer of filler wire and of base metal self-fusion respectively from the top to the bottom of the bead; heat affected zone was narrow showed by the picture of microstructure. The maximum tensile strength of bead was 325MPa that reached 79% of that of base metal by using different laser power. The fracture occurred in fusion zone where the hardness value was low.

Keywords  7A52 aluminum alloy   laser + MIG hybrid welding   bead microstructure    mechanical properties

目  次

1  绪论 1

1．1  选题背景及意义 1

1．2  7A52铝合金的性能及应用 2

1．3  7A52铝合金焊接研究现状 2

1．4  激光+MIG复合焊接技术应用的研究现状 5

1．5  本课题研究主要内容 8

2  试验材料、设备及方法 9

2．1  试验材料 9

2．2  试验设备 10

2．3  试验方法 12

3  7A52铝合金激光+MIG复合焊接工艺对焊缝成形的影响 15

3．1  激光功率对7A52铝合金激光+MIG复合焊接焊缝成形的影响 16

3．2  焊接速度对7A52铝合金激光+MIG复合焊接焊缝成形的影响 17

3．3  MIG焊接电流对7A52铝合金激光+MIG复合焊接焊缝成形的影响 17

3．4  离焦量对7A52铝合金激光+MIG复合焊接焊缝成形的影响