摘要
目的对不同焊接条件下的5454铝合金熔池行为(包括熔池几何特征和液态金属流向)和电弧形态进行研究。方法采用脉冲熔化极惰性气体保护焊(Metal Inert Gas,MIG)和冷金属过渡焊接技术(Cold Metal Transfer,CMT)进行焊接,对不同焊接条件下5454铝合金在堆焊过程中的熔池行为和电弧形态进行观察分析。此外,在进行焊接过程中的温度场分析时,同时考虑了不同保护气体对电弧的影响特征。结果随着焊接保护气体中氦比例的上升,电弧平均直径逐渐减小,稳定性有所改善,电弧的电离能也随之增强,促使电弧在持续稳定燃烧过程中的温度逐步攀升,受电弧影响的最高温度点由纯氩时的1959.1℃上升至纯氦时的2210℃。相比于脉冲MIG,CMT方法的电弧长度更短,熔池尺寸更小,温度更集中,具有更大的液态金属波纹的密度和高度,但起弧时的电弧稳定性较差。结论通过调整保护气体成分,可以显著影响电弧的行为和温度特性;相比于脉冲MIG焊,CMT方法具有更短的电弧长度、更小的熔池尺寸以及更高的温度集中性。虽然起弧时的稳定性较差,但CMT方法形成的焊缝表面的鱼鳞纹质量更高。这种差异主要源于2种焊接方法在电弧控制和熔滴过渡上的区别;彻底清除熔池表面的氧化膜对提高电弧稳定性、减少对熔池的冲击具有显著作用。当熔池表面的氧化膜较少时,电弧稳定性较高,液态金属波纹向熔池边缘扩散的频率和高度变化较小;在焊接作业中,热源生成的温度场呈椭圆状分布,其等温线在热影响区内呈现椭圆形扩展特征。随着保护气体中氦含量的增加,气体的电离电压升高,进而提升了电弧功率,这有助于提升焊接效率和电弧的温度,有效降低焊接过程中的热应力,并促进弧柱收缩,降低熔池的冷却速度,抑制接头中氢气孔的产生。
The work aims to investigate the melt pool behavior(including the geometric characteristics of the melt pool and the liquid metal flow direction)and arc morphology of 5454 aluminum alloy under different welding conditions.Pulsed metal inert gas(MIG)and cold metal transfer(CMT)were used for welding and the melt pool behavior and arc morphology of 5454 aluminum alloy during the overlay welding process under different welding conditions were observed and analyzed.In addition,through the analysis on the temperature field during the welding process,the effect characteristics of different shielding gases on the arc were also considered.As the proportion of helium in the welding shielding gas rose,the average diameter of the arc gradually decreased,the stability was improved,and the ionization energy of the arc was enhanced,which contributed to the gradual increase of the temperature of the arc in the process of continuous and stable combustion,and the highest temperature point affected by the arc increased from 1959.1℃ in pure argon to 2210℃ in pure helium.Compared with pulsed MIG,the CMT method had a shorter arc length,a smaller melt pool size,a more concentrated temperature,and a greater density and height of liquid metal ripples,but the arc stability during arc initiation was poorer.The behavior and temperature characteristics of the arc are significantly affected by varying shielding gas compositions.Compared to pulsed MIG welding,the CMT method contributes to a shorter arc length,a smaller melt pool size,and a higher temperature concentration.Although less stable during arc initiation,the CMT method forms a weld surface with a higher quality of fish scale pattern.This difference mainly stems from the difference between the two welding methods in arc control and droplet transition.The thorough removal of the oxide film on the surface of the melt pool has a significant effect on the improvement of arc stability and the reduction of the impact on the melt pool.When there is less oxide film on the surface of the melt pool,the arc stability is higher,and the frequency and height of the liquid metal ripple spreading to the edge of the melt pool change less.In the welding operation,the temperature field generated by the heat source shows an elliptical distribution,and its isotherms present an elliptical extension characteristic in the heat affected zone.With the increase of helium content in the shielding gas,the ionization voltage of the gas increases,which in turn enhances the arc power,helps to improve the welding efficiency and the temperature of the arc,effectively reduces the thermal stress during the welding process,and promotes the contraction of the arc column,reduces the cooling rate of the melt pool,and inhibits the generation of hydrogen gas holes in the joint.
作者
王刚
李彦青
任泽良
修延飞
刘伟
王厚高
于杰
程琳
豆存印
WANG Gang;LI Yanqing;REN Zeliang;XIU Yanfei;LIU Wei;WANG Hougao;YU Jie;CHENG Lin;DOU Cunyin(Shandong Nuclear Power Equipment Manufacturing Co.,Ltd.,Shandong Yantai 265118,China;Yantai Nuclear Energy Equipment Technology Innovation Center,Shandong Yantai 265118,China)
出处
《精密成形工程》
北大核心
2025年第8期229-237,共9页
Journal of Netshape Forming Engineering
基金
空气导流板铝合金MIG自动焊接样机与工艺研究。
关键词
铝合金
脉冲MIG
电弧形态
熔池特征
保护气体
aluminum alloy
pulsed MIG
arc morphology
melt pool characteristics
shielding gas
