中厚板铝合金双面双弧MIG焊关键工艺问题研究

发布时间：2018-02-01 00:10

  本文关键词： 双面双弧MIG焊 对接接头 T型接头 预热温度 数值仿真　出处：《吉林大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着经济发展和社会城市化建设造成的能源危机和环境污染问题不断加剧,城市轨道客车必然是向着轻量化、节能和环保的方向发展。铝合金具有质量轻、强度高、加工性能好、抗腐蚀性能强等优点,因而增加城市轨道客车中铝合金的使用量是实现城市轨道客车轻量化最直接有效的方法之一。目前,城市轨道客车生产中铝合金的焊接结构一般采用手工电弧焊和半自动焊,工艺落后,产品的质量稳定性差,一次焊接合格率低,生产周期长,生产效率低,并且工人劳动强度大。因此,本文研究了一种中厚板铝合金双面双弧MIG焊工艺方法,并对关键工艺问题进行探究,此工艺减少了工序的复杂程度,免除了清根工序,节约了材料,大大提高了焊接效率,对铝合金在城市轨道客车中的广泛应用具有重要的理论意义和实用价值。本文首先研究了6082-T6铝合金双面双弧MIG焊对接接头和T型接头的微观组织的特点及力学性能。研究结果表明,铝合金双面双弧MIG焊对接接头和T型接头试样的宏观形貌均分为焊缝区、熔合区和热影响区三部分。当预热温度为100℃,焊接电弧前后间距为0 mm时,对接接头打底焊的焊缝金属熔厚最大;当预热温度为100℃,T型接头的根部间隙为3 mm时,T型接头打底焊的焊缝金属熔厚最大。铝合金双面双弧MIG焊对接接头和T型接头试样的微观组织从焊缝区到熔合区依次为树枝晶和柱状晶,晶粒尺寸的大小会随着热输入量的增大而增大,且焊缝侧的柱状晶晶粒的尺寸要大于母材侧柱状晶晶粒的尺寸。当T型接头的根部间隙较小和预热温度过低时,接头容易出现气孔、裂纹和未熔合的焊接缺陷。铝合金双面双弧MIG焊接头的焊缝区有Mg2Si析出。研究发现,铝合金双面双弧MIG焊对接接头和T型接头热影响区的显微硬度低于焊缝区的显微硬度,对接接头热影响区的宽度随着预热温度的升高和焊接电弧前后间距的增大而加宽;T型接头热影响区的宽度随着预热温度的增大而加宽,同时随着根部间隙的增大呈现先增大后减小的现象,且当根部间隙为3 mm时宽度最大。铝合金双面双弧MIG焊对接接头的抗拉强度和屈服强度,随着预热温度的升高和焊接电弧前后间距的增大而有所下降,拉伸断口呈典型的韧窝结构,为韧性断裂。当预热温度为100℃、焊接电弧前后间距为0 mm时,铝合金双面双弧MIG焊对接接头的弯曲试样合格率最高,弯曲性能最好。通过对双面双弧焊对接接头和T型接头的温度场和应力场进行数值仿真分析发现,在合适的工艺条件下,对接接头和T型接头试件两侧的热输入基本对称,并且能够形成共同熔池;应力场的计算结果表明双面双弧焊工艺不仅能够调整试件的残余应力分布,而且在一定程度上能够降低残余应力的水平,这对工件的工艺性以及使用性能都是有利的。
[Abstract]:With the economic development and social urbanization caused by the energy crisis and environmental pollution, urban rail passenger cars are bound to develop towards the direction of lightweight, energy saving and environmental protection. Aluminum alloy has light quality. High strength, good processing performance, strong corrosion resistance and other advantages, so increasing the use of aluminum alloy in urban rail cars is one of the most direct and effective methods to realize the lightweight of urban rail cars. Manual arc welding and semi-automatic welding are generally used in welding structure of aluminum alloy in the production of urban rail cars. The process is backward, the quality stability of the products is poor, the qualification rate of primary welding is low, the production cycle is long, and the production efficiency is low. And the labor intensity of workers is high. Therefore, this paper studies a double-arc MIG welding process for medium and thick aluminum alloy, and probes into the key process issues, this process reduces the complexity of the process. The utility model eliminates the root cleaning process, saves the material and greatly improves the welding efficiency. It has important theoretical significance and practical value for the wide application of aluminum alloy in urban rail passenger cars. In this paper, the microstructure of 6082-T6 aluminum alloy double-side double-arc MIG butt joint and T-joint is studied firstly. The characteristics and mechanical properties of the fabric. The macroscopic morphology of double arc MIG welding butt joint and T type joint of aluminum alloy is divided into three parts: weld zone, fusion zone and heat affected zone. The preheating temperature is 100 鈩，

本文编号：1480371