Simplified Keyhole Plasma Arc Welding Model Based on the Coupling of Arc and Weld Pool

doi:10.3901/JME.2021.18.144

Abstract

Abstract: Based on the multi-physical interaction of electric field, magnetic field, temperature field and flow field, a plasma arc welding (PAW) model coupling both the arc and weld pool is established to reflect the weld pool formation mechanism in the keyhole mode welding. Calculated results show that arc heat flux and arc pressure both appear in a Gaussian distribution, while the pressure striking area is less than the arc heating area. The former is nearly just half of the latter. Weld pool grows in two different stages where it increases fast in the initial stage, but the growth rate drops by over 60% in the second stage. The plasma arc is compressed by electromagnetic force, and the energy density is concentrated. The electromagnetic force in the arc zone is two orders of magnitude higher than that in the weld pool. With the combined effect of arc pressure, Marangoni force and drag force, two symmetrical circular flows appear at the bottom and on the top edge of the weld pool, respectively. And the weld pool gradually turns into a "reversed bugle-like" shape. Experiment is conducted, and the calculated weld fusion line and arc pressure both agree well with experimental results. It's simple and convenient to use the model to guide the PAW engineering application.

Key words: multi-physical interaction, coupled model of arc and weld pool, keyhole mode, heat flux, arc pressure

CLC Number:

TG456

LI Yan, WANG Ling, ZHANG Jixiang, WU Chuansong. Simplified Keyhole Plasma Arc Welding Model Based on the Coupling of Arc and Weld Pool[J]. Journal of Mechanical Engineering, 2021, 57(18): 144-152.

References

[1] LI T Q,WU C S,FENG Y H,et al. Modeling of the thermal fluid flow and keyhole shape in stationary plasma arc welding[J]. International Journal of Heat and Fluid Flow,2012,34(4):117-125.
[2] WU C S,WANG L,REN W J,et al. Plasma arc welding_process,sensing,control and modeling[J]. Journal of Manufacturing Processes,2014,16(1):74-85.
[3] 武传松,王怀刚,张明贤. 小孔等离子弧焊接热场瞬时演变过程的数值分析[J]. 金属学报,2006,42(3):311-316. WU Chuansong,WANG Huaigang,ZHANG Mingxian. Numerical analysis of transient development of temperature field in keyhole plasma arc welding[J]. Acta Metallurgica Sinica,2006,42(3):311-316.
[4] 张晓宇,武传松. 考虑小孔后向偏移的等离子弧焊接热过程模型[J]. 机械工程学报,2015,51(14):66-71.ZHANG Xiaoyu,WU Chuansong. Thermal process model of plasma arc welding with considering the backside keyhole deviation[J]. Journal of Mechanical Engineering,2015,51(14):66-71.
[5] LI Y,FENG Y H,ZHANG X X,et al. An improved simulation of heat transfer and fluid flow in plasma arc welding with modified heat source model[J]. International Journal of Thermal Sciences,2013,64(2):93-104.
[6] 张涛,武传松,陈茂爱. 穿孔等离子弧焊接熔池流动与传热过程的数值模拟[J]. 金属学报,2012,48(9):1025-1032.ZHANG Tao,WU Chuansong,CHEN Maoai. Modelling fluid flow and heat transfer phenomena in keyholing stage of plasma arc welding[J]. Acta Metallurgica Sinica,2012,48(9):1025-1032.
[7] LI T Q,WU C S. Numerical simulation of plasma arc welding with keyhole-dependent heat source and arc pressure distribution[J]. International Journal of Advanced Manufacturing Technology,2015,78(4):593-602.
[8] LI Y,FENG Y H,ZHANG X X,et al. Energy propagation in plasma arc welding with keyhole tracking[J]. Energy,2014,64(1):1044-1056.
[9] LI Y,FENG Y H,ZHANG X X,et al. An evolutionary keyhole-mode heat transfer model in continuous plasma arc welding[J]. International Journal of Heat and Mass Transfer,2018,117(2):1188-1198.
[10] CAI J J,FENG Y H,ZHOU J J,et al. Numerical analysis of weld pool behaviors in plasma arc welding with the lattice Boltzmann method[J]. International Journal of Thermal Sciences,2018,124(2):447-458.
[11] 黄健康,杨茂鸿,余淑荣,等. 旁路耦合微束等离子弧堆垛与熔池动态行为数值模拟[J]. 机械工程学报,2018,54(2):70-76. HUANG Jiankang,YANG Maohong,YU Shurong,et al. Study on the dynamic behavior of molten pool during the stationary pileup of the double-electrode micro plasma arc welding[J]. Journal of Mechanical Engineering,2018,54(2):70-76.
[12] 武传松,孟祥萌,陈姬,等. 熔焊热过程与熔池行为数值模拟的研究进展[J]. 机械工程学报,2018,54(2):1-15.WU Chuansong,MENG Xiangmeng,CHEN Ji,et al. Progress in numerical simulation of thermal processes and weld pool behaviors in fusion welding[J]. Journal of Mechanical Engineering,2018,54(2):1-15.
[13] 陈树君,徐斌,蒋凡. 变极性等离子弧焊电弧物理特性的数值模拟[J]. 金属学报,2017,53(5):631-640. CHEN Shujun,XU Bin,JIANG Fan. Numerical simulation of physical characteristics of variable polarity plasma arc welding[J]. Acta Metallurgica Sinica,2017,53(5):631-640.
[14] 李钊,杨春利,范成磊,等. 新型变极性等离子弧横焊热-力特性及成形研究[J]. 机械工程学报,2017,53(16):156-162. LI Zhao,YANG Chunli,FAN Chenglei,et al. Research on new heat source model of variable polarity plasma arc and welding forming in horizontal position[J]. Journal of Mechanical Engineering,2017,53(16):156-162.
[15] 吴宣楠,冯妍卉,李岩,等. 穿孔等离子弧焊接弧与熔池的耦合模拟及正交分析[J]. 金属学报,2015,51(11):1365-1376.WU Xuannan,FENG Yanhui,LI Yan,et al. Numerical simulation and orthogonal analysis on coupled arc with molten pool for keyholing plasma arc welding[J]. Acta Metallurgica Sinica,2015,51(11):1365-1376.
[16] LI Y,FENG Y H,LI Y F,et al. Plasma arc and weld pool coupled modeling of transport phenomena in keyhole welding[J]. International Journal of Heat and Mass Transfer,2016,92(1):628-638.
[17] XU B,JIANG F,CHEN S J,et al. Numerical analysis of plasma arc physical characteristics under additional constraint of keyhole[J]. Chinese Physics B,2018,27(3):034701.
[18] JIAN X X,WU C S. Numerical analysis of the coupled arc-weld pool-keyhole behaviors in stationary plasma arc welding[J]. International Journal of Heat and Mass Transfer,2015,84(5):839-847.
[19] JIAN X X,WU C S,ZHANG G K,et al. A unified 3D model for an interaction mechanism of the plasma arc,weld pool and keyhole in plasma arc welding[J]. Journal of Physics D:Applied Physics,2015,48(46):465504.
[20] PAN J J,HU S S,YANG L J,et al. Numerical analysis of the heat transfer and material flow during keyhole plasma arc welding using a fully coupled tungsten-plasma-anode model[J]. Acta Materialia,2016,118(10):221-229.
[21] LOWKE J J,TANAKA M. ‘LTE-diffusion approximation’ for arc calculation[J]. Journal of Physics D:Applied Physics,2006,39(16):3634-3643.