镁合金活性激光焊接研究

发布时间：2018-03-20 16:00

本文选题：镁合金　切入点：激光焊接　出处：《华中科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：镁及其合金因为具备密度低、比刚度高、比强度高、易回收等一系列优点,在汽车、航空航天、电子等领域有广阔的应用前景,被称为“21世纪的绿色工程材料”。中国具有较为充足的镁储量,然而镁合金存在的熔点低、反射率高、导热率高等特点,使镁合金连接技术无法在工业上得到大规模的产业化应用。因此,因此开发镁合金先进的连接技术是当前国内外的热门课题。相比一般的镁合金焊接方法,活性焊接具有较小的变形、较高的生产效率、低成本等诸多优点。显然,活性焊接的研究对镁合金产业化的开展具有非常不一般的科学和社会意义。1)本文以AZ31镁合金为研究对象,半导体激光焊和YAG脉冲激光焊为实验设备,研究了氧化物(TiO2和Si O2)、氯化物(CdCl2)、氟化物(CaF2)三类活性剂对激光焊接接头性能的影响规律,利用光学显微镜、扫描电镜、能谱分析仪、维氏显微硬度仪等设备分析了活性剂对半导体激光焊接接头熔深、深宽比以及力学性能的影响。结果表明:不同的活性剂会导致焊缝的熔深和深宽比增加效果不同;活性剂的加入没有改变半导体活性激光焊接接头的显微组织,焊缝的相组成为α-Mg固溶体和β-Mg17Al12,焊缝显微硬度高于母材和热影响区,而热影响区的显微硬度最低;与半导体激光器相比,YAG激光焊所得到的焊接接头更易产生缺陷。2)本文以不同比例成分的TiO2和CaF2为复合活性剂,采用了活性激光焊接方法,研究了其对镁合金AZ31半导体焊接接头熔深、深宽比以及显微硬度的影响规律,寻找最佳TiO2和CaF2配比。结果表明:当复合活性剂中TiO2含量增加,焊缝逐渐变得平滑,但是当TiO2含量大于过大时,焊缝反而变得粗糙;当复合活性剂的成分为80%TiO2+20%CaF2时,焊缝有最大的熔深和深宽比。3)镁合金焊接过程当中常见的主要是气孔、裂纹以及夹杂等缺陷,本文系统分析了引起缺陷产生的各种因素,并提出了预防各类缺陷的一些措施。
[Abstract]:Because of its low density, high specific stiffness, high specific strength and easy to be recycled, magnesium and its alloys have broad application prospects in automotive, aerospace, electronic and other fields. It is called "Green Engineering material in 21th century". China has sufficient magnesium reserves, but magnesium alloys have the characteristics of low melting point, high reflectivity, high thermal conductivity, etc. Therefore, the development of advanced magnesium alloy bonding technology is a hot topic at home and abroad. Active welding has many advantages, such as small deformation, high production efficiency, low cost and so on. Obviously, The research of active welding is of great scientific and social significance to the industrialization of magnesium alloy. 1) this paper takes AZ31 magnesium alloy as research object, semiconductor laser welding and YAG pulse laser welding as experimental equipment. The effects of oxide TIO _ 2 and Sio _ 2O _ 2O _ 2O _ 2O _ 2O _ 2O _ 2O _ 2O _ 2O _ 2O _ 2 on the properties of laser welded joints were studied by means of optical microscope, scanning electron microscope and energy dispersive analyzer. The effects of active agents on the penetration depth, aspect ratio and mechanical properties of semiconductor laser welded joints were analyzed by means of Vickers microhardness tester. The results show that different active agents can increase the weld penetration depth and aspect ratio differently. The phase composition of the weld is 伪 -Mg solid solution and 尾 -Mg17Al12.The microhardness of the weld is higher than that of the base metal and the heat-affected zone, but the microhardness of the heat-affected zone is the lowest. Compared with laser diode laser welding, the welded joints obtained by laser welding are more prone to produce defects. 2) in this paper, the active laser welding method is adopted, in which TiO2 and CaF2 with different proportions are used as composite active agents. The effects of AZ31 on the penetration depth, aspect ratio and microhardness of magnesium alloy AZ31 semiconductor welded joints were studied, and the optimum ratio of TiO2 and CaF2 was found. The results showed that when the content of TiO2 in the composite active agent increased, the weld seam became smooth gradually. However, when the TiO2 content is too large, the weld becomes rough, and when the composition of the composite active agent is 80TiO2 / 20F2, the weld has the largest penetration depth and the ratio of depth to width. In this paper, the factors that cause the defects are analyzed systematically, and some measures to prevent them are put forward.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG456.7

【相似文献】