基于扫描振镜激光-双脉冲CMT复合的铝合金增材气孔抑制机理

doi:10.3901/JME.2025.12.093

摘要/Abstract

摘要： 扫描振镜激光-双脉冲冷金属过渡(Galvanometer scanning laser hybrid double-pulsed cold metal transfer,GSL-D-CMT)复合增材制造铝合金构件具有气孔缺陷少、表面成形质量高的独特优势，在航空航天、核电等领域有着很大的应用潜力。但目前对其抑制或消除气孔缺陷机理尚不明确，直接影响着GSL-D-CMT工艺在高性能铝合金构件制造的工程化应用。为此，基于GSL-D-CMT试验系统深入研究了激光功率因子和光丝间距对复合增材铝合金熔池匙孔动态演化、温度场分布和气孔率的影响规律，揭示了增材氢气孔和匙孔型气孔的成因以及调控振镜激光参量抑制气孔缺陷的物理机制。结果表明，通过耦合扫描振镜激光可消除后退法电弧增材铝合金构件中的密集型气孔；气孔率随激光功率因子和光丝间距的增加呈现出先减小后增大的变化规律，且当激光功率因子为30%时，气孔率最低为0.01%；当光丝间距为5 mm时，气孔率几乎为零。GSL-D-CMT抑制气孔的本质是光束振荡和双脉冲电流加剧了熔池流动，为浅匙孔捕获吞并熔池底部微尺寸气孔提供了良好的动力学条件；较宽光丝间距使熔池温度场分布更均匀、温度梯度减小、凝固速率变缓，匙孔稳定演化的力学边界条件变宽，为熔池微气孔和匙孔捕获大尺寸气孔的逸出创造了良好的热力学条件。

关键词: 铝合金, 扫描振镜激光, 双脉冲CMT, 增材制造, 气孔缺陷

Abstract: The galvanometer scanning laser hybrid double-pulsed cold metal transfer(GSL-D-CMT) additive manufacturing technique has a unique advantage of porosity mitigation and surface quality improvement, and has an important potential application in aerospace, nuclear power field. However, its mechanism for inhibiting pore defects is still unclear, which directly impacts the engineering application of the GSL-D-CMT process in the manufacturing of high-performance aluminum alloy components. To this end, the effects of laser power factor and laser-wire distance on the dynamic evolution, temperature field distribution and porosity formation of molten pool were studied, and the causes of hydrogen pores and keyhole pores and the mechanism of controlling laser parameters to mitigate the porosity defects were revealed in detail. The results indicate that dense pores in aluminum alloy components fabricated by the backward wire WAAM process can be eliminated through coupled galvanometer scanning laser. In this coupled manufacturing process, the porosity exhibits a trend of first decreasing and then increasing as the laser power factor and the laser-wire distance increase. When the laser power factor is 30%, the porosity reaches a minimum of 0.01%. At a laser-wire distance of 5 mm, the porosity is almost 0. The mechanism of GSL-D-CMT inhibiting the porosities lies in the enhanced molten pool convection induced by beam oscillation and double-pulse current, providing favorable kinetic conditions for the shallow keyhole to capture and merge micro-sized pores at the bottom of the molten pool. A wider laser-wire distance results in a more uniform temperature field distribution within the molten pool, reduced temperature gradients, and a slower solidification rate. This broadens the mechanical boundary conditions for stable keyhole evolution and creates favorable thermodynamic conditions for the escape of micro-pores within the molten pool and the capture of larger pores by the keyhole.

Key words: aluminum alloy, galvanometer scanning laser, double pulsed-CMT, additive manufacturing, porosity defects

中图分类号:

TG444

张刚, 蒙旭, 朱明, 石玗, 樊丁. 基于扫描振镜激光-双脉冲CMT复合的铝合金增材气孔抑制机理[J]. 机械工程学报, 2025, 61(12): 93-103.

ZHANG Gang, MENG Xu, ZHU Ming, SHI Yu, FAN Ding. Mechanism of Porosity Mitigation in Aluminum Alloy Additively Manufactured by Galvanometer Scanning Laser Hybrid Double Pulsed-CMT[J]. Journal of Mechanical Engineering, 2025, 61(12): 93-103.

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