激光功率调制对AZ31镁合金焊缝熔深和气孔的影响  

Effects of Laser Power Modulation on Weld Penetration and Pore of AZ31 Magnesium Alloy

作　　者：姜沛佐 董昊 高明月 蔡艳[1,2] Jiang Peizuo;Dong Hao;Gao Mingyue;Cai Yan(School of Materials Science and Engineering,Shanghai Jiao Tong University,Shanghai 200240,China;Shanghai Key Laboratory of Materials Laser Processing and Modification,Shanghai 200240,China)

机构地区：[1]上海交通大学材料科学与工程学院,上海200240 [2]上海市激光制造与材料改性重点实验室,上海200240

出　　处：《中国激光》2023年第12期18-26,共9页Chinese Journal of Lasers

摘　　要：研究了激光功率正弦调制对AZ31镁合金焊缝熔深和工艺气孔的影响。保持激光功率恒定在1500 W,将焊接速度从3.0 m/min逐步增加到4.0 m/min,观察了匙孔周期性开闭行为,分析了不同反射次数对高反射材料匙孔能量分布的影响规律。在不同焊接速度下采用激光功率正弦调制,调制幅度为500 W,调制频率从50 Hz逐步增加至200 Hz,统计了焊缝熔深和工艺气孔率的变化趋势。试验结果表明:对于高反射材料,激光功率调制效果与匙孔内光束反射次数有关,反射次数较多的匙孔具有较大深宽比,匙孔底部累积能量高,深度变化滞后于激光功率变化,激光功率调制有助于增加熔深。激光功率正弦调制不利于镁合金匙孔稳定,50 Hz低频调制显著增加工艺气孔,调制频率为150 Hz时激光功率正弦调制对匙孔稳定性的影响较小。Objective AZ31 magnesium alloy is widely used in the aerospace,automotive,and electronic fields because of its low density,high tensile strength,good conductivity,and electromagnetic shielding effect.Laser welding has the advantages of high energy density,small heat input,easy automation,and good flexibility compared to other welding methods.Therefore,laser welding has significant potential in the field of magnesium alloy welding.However,magnesium alloys have a series of material characteristics,such as a high linear expansion coefficient,easy oxidation,low surface tension,and high reflectivity to lasers.Therefore,magnesium alloy welding joints are prone to defects such as poor weld formation and pores.Researchers have proposed methods to solve such defects.However,most of these methods require the adoption of other methods or processes.Recently,sinusoidal modulation laser welding has been proposed for copper laser welding,and researchers utilized this method for magnesium laser welding.In this study,a regression formula between welding parameters and weld depth is developed.However,limited research has been conducted on the effect of sinusoidal laser power modulation in magnesium alloys,and the relevant mechanism is not completely clear.In this study,the influence of sinusoidal laser power modulation on AZ31 magnesium alloy weld penetration and pores is studied to provide new ideas for the efficient and high-quality welding of magnesium alloys.Methods Sinusoidal modulation laser welding with a wavelength of 1080 nm is utilized for the AZ31 magnesium alloy with a thickness of 4 mm.The average laser power is 1500 W,and the modulation amplitude is 500 W at different frequencies.The welding speed increases from 3.0 m/min to 4.0 m/min with an interval of 0.2 m/min and the modulation frequency increases from 0 to 200 Hz with an interval of 50 Hz.Pure argon is used as the shielding gas at a flow rate of 20 L/min.During the welding process,the molten pool and keyhole are monitored using the combination of an illuminatio

关 键 词：激光技术 镁合金 高反射材料 深熔焊 功率调制 匙孔 

分 类 号：TG457.14[金属学及工艺—焊接]