焊接工艺对铝合金复合焊接接头耐蚀性研究

发布时间：2018-08-29 11:16

【摘要】：5083铝合金为Al-Mg合金,因其具有熔焊性能好、可冷加工及优良的耐蚀性能,使得其广泛应用于航空航天、车辆及船舶等领域。随着该合金及其焊接件的广泛应用,使其面临着严重的腐蚀问题。本试验采用动电位极化曲线测试方法,在3.5%的NaCl所模拟的海水中,对不同工艺条件下10mm厚的5083铝合金YAG激光-MIG电弧平板堆焊接头进行了耐腐蚀性能测试。采用金相显微镜对其微观组织进行观察,并利用高速相机照片和模拟仿真等方法对其形成原因进行了分析。结果表明:由于焊接工艺的不同,使得接头内部缺陷、晶粒的均匀性及应力分布状态不同。在三者的交互作用下,使得电化学稳定性具有一定的差异性,最终导致不同预处理状态下接头耐蚀性,钢刷打磨处理最优,化学腐蚀处理次之,原始表面状态最差。在不同激光功率和焊枪保护气体流量下,接头整体耐蚀性随激光功率和焊枪保护气体流量的增加而降低。在不同焊接电流、光丝距下及焊接速度下,接头耐蚀性随焊接电流、光丝距及焊接速度的增大呈先增强后降低的趋势。在不同离焦量下,接头耐蚀性随着离焦量的变化而波动。接头耐蚀性最优焊接工艺为:钢刷打磨条件下,激光功率为3.0kW、焊接电流为200A、电弧电压为20.8V、光丝距为3mm、焊接速度为1.0m/min、离焦量为-2mm、焊枪保护气流量为20L/min。其耐蚀性约为母材的6.5倍。
[Abstract]:5083 aluminum alloy is a Al-Mg alloy. It is widely used in aerospace, vehicle and ship due to its good welding properties, cold working and corrosion resistance. With the wide application of the alloy and its welding parts, it is faced with serious corrosion problems. The corrosion resistance of 5083 aluminum alloy YAG laser-MIG arc surfacing joints with 10mm thickness under different conditions was tested by potentiodynamic polarization curve test in 3.5% seawater simulated by NaCl. The microstructure was observed by metallographic microscope, and the reasons for its formation were analyzed by means of high speed camera photos and simulation. The results show that the internal defects, grain uniformity and stress distribution are different due to the different welding process. Under the interaction of the three factors, the electrochemical stability is different, which leads to the corrosion resistance of the joints under different pretreatment conditions, the steel brush grinding treatment is the best, the chemical corrosion treatment is the second, and the original surface state is the worst. Under different laser power and flux, the overall corrosion resistance of the joint decreases with the increase of laser power and flux of shielded gas. Under different welding current, light wire distance and welding speed, the corrosion resistance of the joint increases firstly and then decreases with the increase of welding current, optical wire distance and welding speed. The corrosion resistance of the joint fluctuates with the change of the defocus under different defocusing conditions. The optimum welding process for joint corrosion resistance is as follows: laser power is 3.0 kW, welding current is 200A, arc voltage is 20.8V, wire distance is 3mm, welding speed is 1.0 m / min, defocus is -2mm, flux of shielded gas is 20L / min. Its corrosion resistance is about 6.5 times of that of the base metal.
【学位授予单位】：长春理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG457.14

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