大电流GMAW焊接飞溅和烟尘的形态及相结构分析
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摘要
在熔化极气体保护焊(Gas metal arc welding,GMAW)过程中,当熔滴过渡转变为旋转射流过渡时,电弧不稳,焊缝成形变差。在Q235低碳钢上开展工艺试验,探究焊接过程中产生的飞溅和烟尘的形态及相结构。结果表明,高温熔融的金属被甩出雾化,雾滴在飞行过程中球化并快速凝固,飞溅颗粒表面具有特殊形貌,其成分以氧化物为主。电弧燃烧时,焊丝端部形成电流密度很高的斑点,斑点处温度很高,随着焊接电流的增大,金属蒸发量增加。金属蒸发带走了焊丝中大部分的Si、Mn等合金元素,而Si和Mn均是有效脱氧的元素。因此,金属蒸发带走了合金元素,影响O含量,进而影响焊缝性能。烟尘粒径与熔滴过渡方式有关,其粒度范围可达10~(-1)～10~2μm,分布概率较大的是10～60μm的粒子,它能通过人体上呼吸道进入肺部,对人体呼吸系统、神经系统等造成损伤。
In the process of gas metal arc welding(GMAW), the arc is unstable and the formation of the weld becomes worse when the droplet transfer is transformed into a rotating jet. A process tests were carried out on Q235 low carbon steel to explore the morphology and phase structure of the spatter and fume generated during welding. The results showed that the molten metal at high temperature is thrown out and atomized, and the droplets were spheroidized and solidified rapidly during the flight. The surface of the spattered particles exhibited a special appearance, and the particles were mainly composed of oxide. When the arc burned, the spot with high current density formed at the end of the welding wire, and the temperature at the spot was quite high. With the increase of welding current, the amount of metal evaporation increased. Metal evaporation takes away most of the Si, Mn and other alloy elements in the welding wire. While Si and Mn are all effective deoxidizing elements, therefore, the alloying elements was removed by metal evaporation, which affected the content of O, and further exerted negative effect on the weld performance. The particle size of smoke and dust to the mode of droplet transfer, ranging from 10~(-1) μm to 10~2 μm. The majority of particle possessed the size of 10 μm to 60 μm, which could enter the lungs through the upper respiratory tract, and would do harm to the respiratory system and the nervous system of the human body.
In the process of gas metal arc welding(GMAW), the arc is unstable and the formation of the weld becomes worse when the droplet transfer is transformed into a rotating jet. A process tests were carried out on Q235 low carbon steel to explore the morphology and phase structure of the spatter and fume generated during welding. The results showed that the molten metal at high temperature is thrown out and atomized, and the droplets were spheroidized and solidified rapidly during the flight. The surface of the spattered particles exhibited a special appearance, and the particles were mainly composed of oxide. When the arc burned, the spot with high current density formed at the end of the welding wire, and the temperature at the spot was quite high. With the increase of welding current, the amount of metal evaporation increased. Metal evaporation takes away most of the Si, Mn and other alloy elements in the welding wire. While Si and Mn are all effective deoxidizing elements, therefore, the alloying elements was removed by metal evaporation, which affected the content of O, and further exerted negative effect on the weld performance. The particle size of smoke and dust to the mode of droplet transfer, ranging from 10~(-1) μm to 10~2 μm. The majority of particle possessed the size of 10 μm to 60 μm, which could enter the lungs through the upper respiratory tract, and would do harm to the respiratory system and the nervous system of the human body.
引文
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2 Pires I,Quintino L,Miranda R M.Materials and Design,2007,28,1623.
3 Gao S J.Study on smoke and dust measurement and structure of flux cored wire CO2 gas shielded arc welding .Master’s Thesis,Tianjin University,China,2010 (in Chinese).高书俊.药芯焊丝CO2气体保护焊烟尘测试及其结构的研究.硕士学位论文,天津大学,2010.
4 Hua A B,Yin S Y,Chen S J,et al.Journal of Welding,2009,30(8),93(in Chinese).华爱兵,殷树言,陈树君,等.焊接学报,2009,30(8),93.
5 Pu Z X,Pao S K,Wang L S,et al.Journal of Welding,2018,39(2),97 (in Chinese).卜智翔,鲍升凯,王立世,等.焊接学报,2018,39(2),97.
6 Sterjovski Z,Norrish J,Monaghan M B J.Welding in the World,2013,54(9-10),R249.
7 Xu F R.Study on the influence of GMA welding parameters on welding fume.Master’s Thesis,Tianjin University,China,2008 (in Chinese).许芙蓉.GMA焊接工艺参数对焊接烟尘产生影响的研究.硕士学位论文,天津大学,2008.
8 Wu C S,Gao X S.Welding,2018(1),111 (in Chinese).武传松,高学松.焊接,2018(1),111.
9 Tashiro S,Murphy A B,Tanaka M.Welding in the World,DOI:10.1007/s40194-018-0656-9.
10 Moroni B,Viti C.Journal of Aerosol Science,2009,40(11),938.
11 Xu W H,Ye M Q.Machinist,2006(8),23 (in Chinese).徐文汉,叶明强.机械工人,2006(8),23.