發(fā)布時間：2018-03-05 20:23

  本文選題：20Mn2管材　切入點：激光焊接　出處：《遼寧工業(yè)大學》2015年碩士論文　論文類型：學位論文

【摘要】：20Mn2作為一種焊接性良好的結構材料，廣泛的應用在汽車減震器管的焊接制造上。國內(nèi)外對汽車減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，目前尚無光纖激光焊接20Mn2管材的相關研究報道。本文針對20Mn2管材，，進行了激光焊接、活性激光焊接、激光-TIG復合焊接實驗，通過金相顯微鏡、掃描電鏡、顯微硬度計、拉伸性能測試、能譜儀（EDS）等分析手段，對焊接接頭的組織及性能進行了探討，并利用有限元分析軟件對焊接過程溫度場和應力場進行了仿真模擬。 首先，研究了20Mn2管材在不同激光功率、焊接速度、離焦量參數(shù)下經(jīng)激光焊接后的接頭組織及性能。結果表明：當激光功率為2400W，焊接速度為7.3mm/s，離焦量為0mm時，焊縫熔深為最大值4.56mm，熔寬為最大值2.48mm。當激光功率為1200W，焊接速度為7.3mm/s，離焦量為0mm時，焊縫硬度達到最大值382.4HV1.0。焊縫的主要組織為板條馬氏體，熱影響區(qū)的主要組織為鐵素體、珠光體、貝氏體和板條馬氏體。 在激光焊接實驗基礎上，進行了活性激光焊接正交實驗，得到了36.36%SiO2，36.36%TiO2，9.09%Cr2O3，18.18%NaF的最佳活性劑配比，使用此配方活性劑后，焊縫熔深比未涂敷活性劑時增大了24.9%，焊縫顯微硬度比未涂敷活性劑時提高了21.8%，接頭的抗拉強度和延伸率分別達到最大值827.9MPa和13.9%。焊縫成分中出現(xiàn)了O和Si，與活性劑增加熔深的理論完全一致。 其次，研究了20Mn2管材在不同激光功率、焊接電流參數(shù)下經(jīng)激光-TIG復合焊接后的接頭組織與性能。結果表明：當激光功率為2500W，焊接電流為80A時，焊縫熔深達到最大值4.28mm，激光功率對熔寬影響不大；當焊接電流為40A，激光功率為1300W時，焊縫熔寬為最小值1.68mm，焊縫硬度達到最大值372.6HV1.0。焊縫的主要組織同樣為板條馬氏體，熱影響區(qū)的主要組織為鐵素體、珠光體、貝氏體和板條馬氏體。 最后，利用有限元軟件對20Mn2管材的激光焊接和激光-TIG復合焊接進行了溫度場和應力場的仿真模擬，并與實驗結果進行了對比驗證。結果表明：激光焊接和激光-TIG復合焊接的溫度場和應力場分布極為相似。激光焊接過程中，焊縫中心可達到的最高溫度為2401℃，等效應力最大值為215.9MPa，在管材的激光-TIG復合焊接過程中，焊縫中心可達到的最高溫度為2766℃，等效應力最大值為216.5MPa，焊縫宏觀形貌的模擬結果與實驗結果基本吻合。
[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

本文編號：1571739