20Mn2管材的光纤激光焊接及数值模拟

发布时间：2018-03-05 20:23

  本文选题：20Mn2管材　切入点：激光焊接　出处：《辽宁工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：20Mn2作为一种焊接性良好的结构材料，广泛的应用在汽车减震器管的焊接制造上。国内外对汽车减震器管材焊接方法的研究主要采用的是摩擦焊等焊接方法，目前尚无光纤激光焊接20Mn2管材的相关研究报道。本文针对20Mn2管材，，进行了激光焊接、活性激光焊接、激光-TIG复合焊接实验，通过金相显微镜、扫描电镜、显微硬度计、拉伸性能测试、能谱仪（EDS）等分析手段，对焊接接头的组织及性能进行了探讨，并利用有限元分析软件对焊接过程温度场和应力场进行了仿真模拟。 首先，研究了20Mn2管材在不同激光功率、焊接速度、离焦量参数下经激光焊接后的接头组织及性能。结果表明：当激光功率为2400W，焊接速度为7.3mm/s，离焦量为0mm时，焊缝熔深为最大值4.56mm，熔宽为最大值2.48mm。当激光功率为1200W，焊接速度为7.3mm/s，离焦量为0mm时，焊缝硬度达到最大值382.4HV1.0。焊缝的主要组织为板条马氏体，热影响区的主要组织为铁素体、珠光体、贝氏体和板条马氏体。 在激光焊接实验基础上，进行了活性激光焊接正交实验，得到了36.36%SiO2，36.36%TiO2，9.09%Cr2O3，18.18%NaF的最佳活性剂配比，使用此配方活性剂后，焊缝熔深比未涂敷活性剂时增大了24.9%，焊缝显微硬度比未涂敷活性剂时提高了21.8%，接头的抗拉强度和延伸率分别达到最大值827.9MPa和13.9%。焊缝成分中出现了O和Si，与活性剂增加熔深的理论完全一致。 其次，研究了20Mn2管材在不同激光功率、焊接电流参数下经激光-TIG复合焊接后的接头组织与性能。结果表明：当激光功率为2500W，焊接电流为80A时，焊缝熔深达到最大值4.28mm，激光功率对熔宽影响不大；当焊接电流为40A，激光功率为1300W时，焊缝熔宽为最小值1.68mm，焊缝硬度达到最大值372.6HV1.0。焊缝的主要组织同样为板条马氏体，热影响区的主要组织为铁素体、珠光体、贝氏体和板条马氏体。 最后，利用有限元软件对20Mn2管材的激光焊接和激光-TIG复合焊接进行了温度场和应力场的仿真模拟，并与实验结果进行了对比验证。结果表明：激光焊接和激光-TIG复合焊接的温度场和应力场分布极为相似。激光焊接过程中，焊缝中心可达到的最高温度为2401℃，等效应力最大值为215.9MPa，在管材的激光-TIG复合焊接过程中，焊缝中心可达到的最高温度为2766℃，等效应力最大值为216.5MPa，焊缝宏观形貌的模拟结果与实验结果基本吻合。
[Abstract]:As a kind of good weldability structural material, 20Mn2 is widely used in the welding manufacture of automobile shock absorber pipe. There is no related research report on the fiber laser welding of 20Mn2 pipe. In this paper, the experiments of laser welding, active laser welding and laser TIG composite welding for 20Mn2 pipe are carried out, and the results are as follows: metallographic microscope, scanning electron microscope, microhardness meter, etc. The microstructure and properties of welded joints were discussed by means of tensile test and EDS. The temperature and stress fields in welding process were simulated by finite element analysis software. Firstly, the microstructure and properties of 20Mn2 pipe welded by laser at different laser power, welding speed and defocus parameters are studied. The results show that when the laser power is 2400W, the welding speed is 7.3mm / s, the defocus is 0mm. The weld penetration depth is 4.56mm, the weld width is 2.48mm. when the laser power is 1200W, the welding speed is 7.3mm / s, and the defocus is 0mm, the weld hardness reaches the maximum 382.4HV1.0.The main microstructure of the weld is lath martensite, and the main microstructure of the heat-affected zone is ferrite. Pearlite, bainite and lath martensite. On the basis of laser welding experiment, the orthogonal experiment of active laser welding was carried out, and the optimum proportion of active laser welding agent was obtained by 36.36SiO2and 36.36TiO29.09Cr2O39.09Cr2O3and 18.18NaF. The weld penetration depth increased 24.9. the weld microhardness increased 21.8. the tensile strength and elongation reached the maximum value of 827.9MPa and 13.9MPa respectively. O and Si-were found in the weld composition, which were similar to those of the active agent, and the tensile strength and elongation of the weld joint reached the maximum value of 827.9MPa and 13.9MPa respectively. The theory of increasing penetration is in complete agreement. Secondly, the microstructure and properties of 20Mn2 pipe welded by laser TIG composite welding under different laser power and welding current parameters are studied. The results show that when the laser power is 2500W, the welding current is 80A, When the welding current is 40A and laser power is 1300W, the weld width is minimum 1.68mm, and the maximum weld hardness is 372.6HV1.0.The main microstructure of the weld is also lath martensite. The main structures of the HAZ are ferrite, pearlite, bainite and lath martensite. Finally, the temperature field and stress field of 20Mn2 pipe were simulated by using finite element software. The results are compared with the experimental results. The results show that the distribution of temperature field and stress field of laser welding and laser TIG composite welding are very similar. The maximum temperature of weld center is 2401 鈩

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