高强铝合金螺柱TIG-拉弧焊接工艺研究

发布时间：2018-07-20 19:22

【摘要】：针对中大直径高强铝合金螺柱焊接中存在的易烧损、未熔合、气孔多、易氧化等技术问题,本论文以Φ18mm的5A06高强铝合金螺柱为研究对象,以TIG-拉弧复合热源螺柱焊接为基本焊接方法,开展了对螺柱焊接的保护装置和保护形式及其复合工艺规范的设计研究。并根据螺柱接头的力学性能、微观组织形态,对高强铝合金螺柱焊接的复合工艺方法进行了综合评估分析与优化。本论文所设计的气体保护装置主要包含与螺柱焊枪配合的保护气罩主体,与不同尺寸螺柱夹套配合的气罩顶盖,与陶瓷圈配合的气罩底盖。该保护装置针对焊缝部位的惰性气体氛围设计了独立气室,有效降低了焊接过程中熔池部位的氧化,而且本装置可以匹配不同直径的螺柱,一套保护装置即可适应全尺寸螺柱,解决了工程应用中气体保护装置适应性差的问题。本论文利用单因素法分析了各工艺参数对7A52铝板焊缝成形的影响,确定了三个主要工艺参数的选择范围,利用正交试验找到了最优工艺参数,并通过极差分析和方差分析对试验结果进行了优化,优化后的接头抗剪强度达到了176.4MPa,比正交结果最好的一组提高了5%,确定优化后的工艺参数为最优工艺规范,并以此为参考确定了5A06铝板的最优工艺规范,获得了抗剪强度达184 MPa的螺柱接头。在正交试验优化的工艺规范基础之上,本论文研究了高强铝合金螺柱焊接复合工艺方法,分析了混合惰性气体及汽态钎剂对焊缝的保护作用,得出氦气与氩气按2：8配比的混合气体与汽态钎剂保护复合工艺对高强铝合金螺柱焊接保护效果更好,因为氦气氛围下的电弧能量更集中,对氧化膜与二次氧化的阻止更充分,增强了熔池的流动性,辅以汽态钎剂对熔池的主动清理作用,焊缝组织性能得到了极大改善,该复合工艺方法下的焊缝抗剪强度较纯氩保护下的焊缝强度提高了10%以上。
[Abstract]:In order to solve the technical problems of high strength aluminum alloy stud welding with medium and large diameter, such as easy burning, non-fusion, large porosity and easy oxidation, this paper takes 桅 18mm 5A06 high strength aluminum alloy stud as the research object. Based on the welding method of TIG-arc composite heat source stud welding, the design and research of the protective device and protective form of stud welding and its composite process specification are carried out. According to the mechanical properties and microstructure of stud joint, the composite process of high strength aluminum alloy stud welding was evaluated and optimized. The gas protection device designed in this paper mainly consists of the main body of the gas shield matched with the stud welding gun, the top cover of the gas cover with different sizes of stud clamps, and the bottom cover of the gas cover with ceramic ring. The protective device designed an independent gas chamber for the inert gas atmosphere of the weld seam, effectively reducing the oxidation of the weld pool during the welding process, and the device can match the studs of different diameters, and a set of protective devices can adapt to the full-size studs. The problem of poor adaptability of gas protector in engineering application is solved. In this paper, single factor method is used to analyze the influence of process parameters on 7A52 aluminum sheet weld forming, and the selection range of three main process parameters is determined, and the optimum process parameters are found by orthogonal test. The test results were optimized by means of range analysis and variance analysis. The shear strength of the joints reached 176.4 MPa after optimization, which was 5 times higher than that of the best group of orthogonal results. The optimized process parameters were determined to be the optimal process specifications. The optimum process specification for 5A06 aluminum plate was determined and the stud joint with shear strength of 184MPa was obtained. On the basis of the optimized process specification of orthogonal test, the composite process of stud welding of high strength aluminum alloy was studied in this paper, and the protective effect of mixed inert gas and vapor flux on weld seam was analyzed. It is concluded that the composite process of helium and argon mixture gas and vapor flux protection at 2:8 is better for the welding protection of high strength aluminum alloy studs, because the arc energy is more concentrated in helium atmosphere. The resistance to oxide film and secondary oxidation is more adequate, the fluidity of the molten pool is enhanced, and the weld structure and properties are greatly improved by the active cleaning effect of the vapor flux on the weld pool. The shear strength of the weld is increased by more than 10% compared with that of the pure argon protection.
【学位授予单位】：南京理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG457.14

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