2219铝合金TIG焊及FSW焊残余应力研究

发布时间：2018-06-04 09:18

本文选题：2219铝合金 + X射线衍射　；参考：《哈尔滨工业大学》2017年硕士论文

【摘要】：2219铝合金以其高强度及良好的断裂韧性等优点而被广泛用于航天火箭燃料槽与氧化剂槽等方面,其焊接件的焊接残余应力严重影响到焊接结构的使用性和结构安全可靠性。感应加热技术在加热时热源集中、加热效率高以及可实现局部热处理等优点,使其可以成为有效的大型焊接件残余应力去除技术,但目前针对2219铝合金焊接件感应加热热处理去应力的研究较少。本文通过有限元模拟和X射线衍射法开展对2219铝合金不同焊接方法的残余应力表征和感应加热热处理去应力技术的研究。针对X射线应力测量方法,研究了物理和化学两种抛光预处理工艺以及粗糙度对表面应力测量结果的影响。测试结果表明,化学抛光方法与物理抛光方法相比,处理后的样品表面形貌锯齿状尖端更少以及不产生附加的表面变形扰动层。同时样品表面粗糙度对于X射线应力测量结果影响较大,实验结果表明,粗糙度降低到一定范围内时,测量结果稳定,接近真实值。采用MSC.Marc商业有限元模拟软件开展对2219铝合金钨极氩弧熔焊和搅拌摩擦不同焊接方法的残余应力有限元模拟,通过模拟和X射线法实测对比不同焊接方法下2219铝合金焊后残余应力场的大小和分布特征;通过二次开发子程序编译,实现基于搅拌针热源和热机耦合模型下2219铝合金搅拌摩擦焊残余应力的模拟,同时研究一定范围内,焊接速度和主轴转数对该模型下焊接温度和残余应力的影响。结果表明,两种不同焊接方法有限元模拟计算的焊缝区域尺寸与实测结果吻合,X射线应力测试结果与有限元模拟结果一致,证明了焊接热源模型和力学计算的合理性,对比结果显示搅拌摩擦焊可以实现较小残余应力的焊接。通过感应加热装置,实现了对2219铝合金焊接件焊缝区域的局部去应力热处理,结果显示,在时效温度范围内,随着感应加热温度的提高,残余应力峰值不断降低,其中拉应力峰值降低明显,热处理温度越高,应力分布越趋近于均匀化。通过MSC.MARC子程序编译实现了感应加热热处理的计算,热循环测试结果以及X射线应力测试结果与计算结果吻合,证明了简化等密度感应加热热源有限元模拟的合理性。
[Abstract]:2219 aluminum alloy has been widely used in space rocket fuel tank and oxidant tank due to its high strength and good fracture toughness. The welding residual stress of the welded parts seriously affects the serviceability of the welded structure and the safety and reliability of the structure. Induction heating technology has the advantages of concentrated heat source, high heating efficiency and local heat treatment, which makes it an effective residual stress removal technology for large welded parts. However, there are few researches on induction heating and heat treatment of 2219 aluminum alloy welds. In this paper, finite element simulation and X-ray diffraction method are used to study the residual stress characterization of different welding methods of 2219 aluminum alloy and the technique of heat treatment of induction heating to remove stress. Aiming at the X-ray stress measurement method, the physical and chemical pretreatment processes and the effect of roughness on the surface stress measurement results are studied. The test results show that compared with physical polishing, the surface morphology of the treated samples has fewer zigzag tip and no additional surface deformation disturbance layer. At the same time, the surface roughness of the sample has a great influence on the X-ray stress measurement results. The experimental results show that when the roughness decreases to a certain range, the measured results are stable and close to the real value. MSC.Marc commercial finite element simulation software was used to simulate the residual stress of 2219 aluminum alloy welding by argon tungsten arc welding and friction stir welding. The size and distribution of residual stress field of 2219 aluminum alloy after welding were compared by simulation and X-ray method. The residual stress of 2219 aluminum alloy friction stir welding is simulated based on the coupling model of heat source and heat engine. The effects of welding speed and spindle rotation number on the welding temperature and residual stress in the model are also studied. The results show that the size of weld zone calculated by finite element simulation of two different welding methods is in agreement with the measured results. The results of X-ray stress measurement are in agreement with the results of finite element simulation, which proves the rationality of welding heat source model and mechanical calculation. The results show that friction stir welding can realize the welding of small residual stress. By means of induction heating device, the local stress-free heat treatment of weld area of 2219 aluminum alloy welds is realized. The results show that the peak value of residual stress decreases with the increase of induction heating temperature in the range of aging temperature. The peak value of tensile stress decreases obviously, and the higher the heat treatment temperature, the more homogeneous the stress distribution is. The calculation of induction heating heat treatment is realized by MSC.MARC subprogram. The results of thermal cycle test and X-ray stress test are in agreement with the calculated results, which proves the rationality of simplified finite element simulation of induction heating heat source with equal density.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG457.14

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