改善铝合金激光-TIG复合焊接头性能的工艺研究

发布时间：2018-01-16 23:10

本文关键词：改善铝合金激光-TIG复合焊接头性能的工艺研究　出处：《合肥工业大学》2017年硕士论文　论文类型：学位论文

【摘要】：2A14铝合金具有质量轻,耐热性好,低温性能好等优点,广泛应用于航空航天、船舶制造等领域。对铝合金采用激光电弧复合焊接工艺是目前研究的热点,传统铝合金电弧焊接容易发生翘曲、接头软化等问题。激光电弧复合焊接避免了单一热源焊接的缺陷,使得焊接过程的稳定性和焊缝成形得到显著改善。目前,铝合金激光电弧复合焊接工作大多集中在激光与MIG电弧的复合研究上,而铝合金激光-TIG复合焊接的研究较少,尤其激光与TIG电弧之间的复合模式以及改善接头强度的研究更是鲜有报道。本文采用LWS-1000型Nd:YAG激光器和WSM-400(PNE61-400P)数字化焊机,对3 mm 2A14铝合金进行激光-TIG复合焊接,研究焊前对板材进行黑化或加粉工艺,对焊缝成形、显微组织以及接头力学性能的影响,并且通过添加不同成分配比的TiC粉和Al粉,以探究改善接头强度的工艺。此外,还分析不同复合模式对焊缝成形、显微组织等的影响,深入探究其影响机理。最后探究热处理工艺对铝合金激光-TIG复合焊接接头的抗拉强度的影响。在2A14铝合金的激光-TIG复合焊接过程中,焊前黑化处理的工艺或添加TiC的工艺都可以改善铝合金对激光的吸收率,但是黑化处理工艺对激光吸收率的提高效果大于加粉处理。黑化处理的宽度变化对焊缝成形的影响不显著。焊前涂覆TiC和Al粉的工艺方法可以有效改善焊接接头的抗拉强度,经过热处理后的2A14纯母材的抗拉强度大约为279.14 MPa,焊前没有经过加粉处理所得焊接接头的抗拉强度平均值为184.33 MPa,为母材的66%。当添加TiC为10%时,所得接头强度平均值为252.90 MPa,约为母材的90.60%。在焊接工艺参数相同时,激光导前获得的焊缝表面成形质量良好,焊缝表面略微凹陷,熔宽、熔深大,焊缝显微组织更均匀化。而电弧导前获得的焊缝表面严重发黑,焊缝表面略微隆起,熔宽、熔深小;激光导前模式和电弧导前模式的根本区别在于激光导前时激光击破铝合金表面的氧化膜,从而导致在整个焊接过程中能量的有效利用率不同。热处理工序的有无以及热处理工艺的先后顺序对焊接接头的抗拉强度都有影响;进行热处理得到的接头强度大于不热处理接头的抗拉强度;退火态2A14先焊接,再对得到的接头热处理,可以获得抗拉强度最高的焊接接头。
[Abstract]:2A14 aluminum alloy has the advantages of light weight, good heat resistance and good low temperature performance. It is widely used in aerospace, shipbuilding and other fields. Conventional arc welding of aluminum alloy is prone to warpage and joint softening. Laser arc composite welding avoids the defects of single heat source welding and makes the stability of welding process and weld formation significantly improved. The research of laser arc composite welding of aluminum alloy is mostly focused on the combination of laser and MIG arc, but the research of laser TIG composite welding of aluminum alloy is less. Especially the recombination mode between laser and TIG arc and the study of improving the strength of joint are rarely reported. In this paper, LWS-1000 type Nd:YAG laser and WSM-400 are used. PNE61-400P) Digital welder. The laser TIG composite welding of 3mm 2A14 aluminum alloy was carried out, and the effects of blackening or powder addition on the weld formation, microstructure and mechanical properties of the joint were studied. And by adding TiC powder and Al powder with different composition, the process of improving joint strength was explored. In addition, the influence of different composite modes on weld formation and microstructure was also analyzed. Finally, the effect of heat treatment on the tensile strength of laser TIG composite welding joint of aluminum alloy was investigated. In the laser TIG composite welding process of 2A14 aluminum alloy. The laser absorptivity of aluminum alloy can be improved by the process of blackening before welding or adding TiC. However, the effect of blackening treatment on laser absorptivity is greater than that of powder addition. The width change of blackening treatment has no significant effect on weld formation. The process of coating TiC and Al powder before welding can effectively improve welding. Tensile strength of joint. The tensile strength of 2A14 pure base metal after heat treatment is about 279.14 MPa, and the average tensile strength of welded joint without adding powder before welding is 184.33 MPa. When the TiC is 10, the average strength of the joint is 252.90 MPa, about 90.60 of the base metal. When the welding process parameters are the same. The weld surface obtained before laser conduction is of good quality, the weld surface is slightly sunken, the weld surface is slightly sunken, the weld surface is wide, the penetration depth is large, and the microstructure of the weld is more homogeneous, while the weld surface obtained before the arc conduction is seriously blackened. The weld surface is slightly raised, and the weld is wide and deep. The fundamental difference between the laser front mode and the arc front mode is that the laser breaks the oxide film on the surface of aluminum alloy. As a result, the effective utilization rate of energy in the whole welding process is different. The existence of heat treatment process and the sequence of heat treatment process have influence on the tensile strength of welded joint. The strength of the joint obtained by heat treatment is higher than that of the joint without heat treatment. The welded joints with the highest tensile strength can be obtained by annealing 2A14 first and then heat treated the obtained joints.
【学位授予单位】：合肥工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG407

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