Study on the Keyhole Effects in DP-VPTIG Welding of Medium-thick Aluminum Alloys

doi:10.3901/JME.2025.06.133

Abstract

Abstract: Double-pulsed variable polarity TIG welding brings about deep penetration welding of medium-thick aluminum alloy structures by stimulating a keyhole in the weld pool. The dynamic behavior and morphological characteristics of the keyhole have a significant impact on the weld formation. In order to explore the effects of the keyhole on the weld penetration, the dynamic evolution law of the keyhole in various pulse cycles is obtained and analyzed by using high-speed image acquisition technology. A transient numerical model of the welding process is established based on computational fluid dynamics. The dynamic characteristics of the temperature field and flow field of the weld pool and the relationship between keyhole and the weld pool are analyzed by using this model. The research results show that the weld pool exhibits various dynamic behaviors with the pulsating current. The keyhole is formed at the low-frequency pulse peak stage, and causes the welding heat source moving downward and excites a high-speed heat transfer channel in the weld pool, which can improve the heat transfer efficiency of the arc towards weld pool bottom and promote the increase of the weld pool depth. Moreover, there is a mutual promotion relation between the depth of keyhole and weld pool, which further improves the penetration.

Key words: medium-thick aluminum alloy, pulse modulated arc, keyhole welding, numerical simulation, weld formation

CLC Number:

TG456

JIANG Zihao, XIAO Hong, ZENG Caiyou, ZHANG Quan, YANG Qingfu, XIE Fei, MA Kang, WANG Yasen, QI Bojin, CONG Baoqiang. Study on the Keyhole Effects in DP-VPTIG Welding of Medium-thick Aluminum Alloys[J]. Journal of Mechanical Engineering, 2025, 61(6): 133-140.

References

[1] 姚君山，徐萌，贾洪德，等. 推进剂贮箱先进焊接工艺研究进展[J]. 航空制造技术，2008(8)：32-35. YAO Junshan，XU Meng，JIA Hongde，et al. Research progress of advanced welding technology for propellant tanks[J]. Aeronautical Manufacturing Technology，2008(8)：32-35.
[2] 从保强，苏勇，齐铂金，等. 铝合金脉冲电弧焊接技术进展[J]. 航空制造技术，2016(11)：41-46. CONG Baoqiang，SU Yong，QI Bojin，et al. Advances in pulsed arc welding technology for aluminum alloys[J]. Aeronautical Manufacturing Technology，2016(11)：41-46.
[3] 张抱日，顾盛勇，石永华. 基于焊缝熔透检测的机器人深熔K-TIG焊接系统[J]. 机械工程学报，2019，55(17)：14-21. ZHANG Baori，GU Shengyong，SHI Yonghua. Robotic deep penetration K-TIG welding system based on weld penetration detection[J]. Journal of Mechanical Engineering，2019，55(17)：14-21.
[4] HUANG Y，LIU R，HAO Y. Gas pool coupled activating TIG welding method with coupling arc electrode[J]. Chinese Journal of Mechanical Engineering，2018，31(6)：169-176.
[5] XIANG J，TANAKA K，CHEN F，et al. Modelling and measurements of gas tungsten arc welding in argon-helium mixtures with metal vapour[J]. Welding in the World，2021，65(4)：767-783.
[6] 孙清洁，林三宝，杨春利，等. 超声钨极氩弧复合焊接电弧压力特征研究[J]. 机械工程学报，2011，47(4)：53-57，65. SUN Qingjie，LIN Sanbao，YANG Chunli，et al. Characteristic of arc pressure in ultrasonic-TIG hybrid welding[J]. Journal of Mechanical Engineering，2011，47(4)：53-57，65.
[7] WANG Z，JIANG D，WU J，et al. A review on high-frequency pulsed arc welding[J]. Journal of Manufacturing Processes，2020，60：503-519.
[8] 齐铂金，杨舟，杨明轩，等. 超高频脉冲GTAW工艺特性分析[J]. 机械工程学报，2016，52(2)：26-32. QI Bojin，YANG Zhou，YANG Mingxuan，et al. Analysis on characteristic of ultra high frequency pulsed gas tungsten arc welding process[J]. Journal of Mechanical Engineering，2016，52(2)：26-32.
[9] WANG Y，LI H，LI Z，et al. Refining microstructure of medium-thick AA2219 aluminium alloy welded joint by ultrasonic frequency double-pulsed arc[J]. Journal of Materials Research and Technology，2023，23：3048-3061.
[10] WANG Y，CONG B，QI B，et al. Process characteristics and properties of AA2219 aluminum alloy welded by double pulsed VPTIG welding[J]. Journal of Materials Processing Technology，2019，266：255-263.
[11] WANG Y，CONG B，QI B，et al. Influence of low-pulsed frequency on arc profile and weld formation characteristics in double-pulsed VPTIG welding of aluminium alloys[J]. Journal of Manufacturing Processes，2020，58：1211-1220.
[12] LU F，TANG X，YU H，et al. Numerical simulation on interaction between TIG welding arc and weld pool[J]. Computational Materials Science，2006，35(4)：458-465.
[13] WANG H，WEI Y，YANG C. Numerical calculation of variable polarity keyhole plasma arc welding process for aluminum alloys based on finite difference method[J]. Computational Materials Science，2007，40(2)：213-225.
[14] 柯文超，从保强，祁泽武，等. NiTi形状记忆合金电弧熔融涂覆及微连接机理[J]. 机械工程学报，2022，58(2)：176-184. KE Wenchao，CONG Baoqiang，QI Zewu，et al. Arc melting coating and micro-joining mechanism of NiTi shape memory alloy[J]. Journal of Mechanical Engineering，2022，58(2)：176-184.
[15] PAN J，HU S，YANG L，et al. Simulation and analysis of heat transfer and fluid flow characteristics of variable polarity GTAW process based on a tungsten arc specimen coupled model[J]. International Journal of Heat and Mass Transfer，2016，96：346-352.
[16] XU B，TASHIRO S，JIANG F，et al. The effect of electrode energy balance on variable polarity plasma arc pressure[J]. International Journal of Heat and Mass Transfer，2019，145：118715.
[17] 潘家敬. 铝合金非熔化极变极性焊接电弧与熔池特性数值分析[D]. 天津：天津大学，2017. PAN Jiajing. Numerical analysis of the arc and molten pool characteristics in non-consumable electrode variable polarity arc welding of alumium process[D]. Tianjin：Tianjin University，2017.
[18] 孟祥萌. 高速GTAW焊缝表面成形缺陷的形成机理及其抑制措施[D]. 济南：山东大学，2017. MENG Xiangmeng. Formation mechanism of weld appearance defects in high-speed GTAW and their suppression measures[D]. Jinan：Shandong University，2017.
[19] 从保强，齐铂金，杨明轩，等. HPVP-GTAW电弧力及焊接质量分析[J]. 焊接学报，2013，34(1)：21-24，114. CONG Baoqiang，QI Bojin，YANG Mingxuan，et al. HPVP-GTAW arc force and welding quality analysis[J]. Transactions of The China Welding Institution，2013，34(1)：21-24，114.
[20] WANG Y，QI B，CONG B，et al. Arc characteristics in double-pulsed VP-GTAW for aluminum alloy[J]. Journal of Materials Processing Technology，2017，249：89-95.