Effect of Weldment Inclination Angle and Variable Polarity Plasma Assistance on Porosity Defects in Laser Welding

GAO Yuehua; PENG Lichang; XU Muzhong; XIONG Zhihao; LIU Qipeng; LIAO Fangfang; WANG Shanlin; KE Liming

doi:10.3969/j.issn.1674-6457.2026.05.010

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Journal of Netshape Forming Engineering ›› 2026, Vol. 18 ›› Issue (5) : 114-122. DOI: 10.3969/j.issn.1674-6457.2026.05.010

Advanced Joining Technology

Effect of Weldment Inclination Angle and Variable Polarity Plasma Assistance on Porosity Defects in Laser Welding

GAO Yuehua¹, PENG Lichang¹, XU Muzhong², XIONG Zhihao¹, LIU Qipeng^1,*, LIAO Fangfang², WANG Shanlin¹, KE Liming²

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Abstract

To solve the problem that pores are prone to occur in laser deep penetration welding of thick-plate aluminum alloys, the work aims to explore the mitigating effect of weldment inclination angle and variable polarity plasma assistance on the pore defects in laser welding. Two methods, namely laser welding and laser-variable polarity plasma hybrid welding, were employed to conduct autogenous welding tests on 5083 aluminum alloy under different weldment inclination angles. X-ray detection technology was used to detect porosity defects and analyze the porosity rate. Both methods resulted in metallurgical (hydrogen-induced) pores and process pores in the welded seams. When the weldment inclination angle increased from 0° to 40°, the porosity of laser welding decreased from 7.45% to 2.48%, and that of laser-variable polarity plasma hybrid welding decreased from 3.91% to 1.10%. Under the same weldment inclination angle, the number and size of pores in laser-variable polarity plasma hybrid welding were smaller than those in laser welding, with an average reduction in porosity of approximately 55%. With the increase of the weldment inclination angle, the change in the direction of gravitational force, on the one hand, improves the stability of the molten pool, and on the other hand, increases the force for bubbles to escape toward the keyhole and shortens the escape path of bubbles. Therefore, the weldment inclination angle has a mitigating effect on porosity defects. Due to the addition of the variable polarity plasma arc, its cleaning ability helps reduce the generation of hydrogen-induced pores, and its stirring effect on the molten pool also promotes the rapid escape of bubbles. Thus, the variable polarity plasma assistance can significantly reduce porosity defects.

Key words

laser welding / hybrid welding / weldment inclination angle / aluminum alloy / process pores / metallurgical pores

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GAO Yuehua, PENG Lichang, XU Muzhong, XIONG Zhihao, LIU Qipeng, LIAO Fangfang, WANG Shanlin, KE Liming. Effect of Weldment Inclination Angle and Variable Polarity Plasma Assistance on Porosity Defects in Laser Welding[J]. Journal of Netshape Forming Engineering. 2026, 18(5): 114-122 https://doi.org/10.3969/j.issn.1674-6457.2026.05.010

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Funding

National Natural Science Foundation of Jiangxi Province (20232ACB204020); Open Project of Jiangxi Key Laboratory of Aerospace Component Forming and Joining(EL202303270); Zhejiang Province “Jianbing” “Lingyan” Research and Development Plan(2023C01244); Jiangxi Provincial Key Research and Development Project (20241ZDD02017)