摘要
焊接熔池流体的流动行为与接头的力学性能密切相关,因此对焊接温度场和流场进行研究具有重要的理论和实际意义。采用数值模拟技术对焊接温度场和流场进行计算,结果表明:振荡激光束产生的熔池搅拌作用有助于促进传热,从而降低了焊接熔池的温度梯度;振荡激光束搅拌熔池可以驱动流体沿同一方向流动并形成涡流,从而增加了焊接熔池的稳定性;当振荡频率为100 Hz时,可以形成一个流速高达0.7 m/s的涡流,该涡流可以显著提高熔池的稳定性;采用振荡激光束对熔池进行搅拌可以起到熔池除气、细化焊缝晶粒、促进焊缝中β相析出等作用;随着振荡频率由0 Hz增加到100 Hz,焊缝中β相的面积分数由3.37%增加到12.3%,焊缝气孔率由5.02%降低到0.2%。
Objective Because the fluid flow behavior in a molten pool is closely associated with the mechanical properties of the joint,the analyses and regulation of welding temperatures and flow fields are of great practical importance.The main objectives of this study are to reveal the interaction of the oscillating laser beam with the molten pool and to elucidate the underlying relationship between the welding temperature and flow fields as well as the microstructure of the joint.Methods The welding experiments were conducted using an oscillating laser wirefilling welding system with a butt joint configuration.A threedimensional transient multiphysical numerical model was constructed to simulate the oscillating laser welding process of 5083 aluminum alloy.The microstructures of the joints were observed using an AOSVI M320PHK830 polarizing microscope(PM)and a Zeiss Ultra 55 LE scanning electron microscope(SEM).The chemical compositions of the different phases of the joints were analyzed using an XFlash®4010 energy dispersive spectroscope(EDS)detector.Xray diffraction(XRD)analyses of the joints were performed using a D8 Advance Xray diffractometer for phase identification.Nondestructive Xray testing was performed to detect weld pores.Results and Discussions The results show that molten pool stirring produced by an oscillating laser beam facilitates heat transfer and thus reduces the temperature gradient of the molten pool.In addition,the oscillating laser beam stirs the molten pool to drive the fluid flow in the same direction and form vortices,thereby increasing the stability of the molten pool.When the oscillaton frequency is 100 Hz,a vortex with a flow rate of up to 0.7 m/s is formed,which significantly improves the stability of the molten pool.Furthermore,degassing the molten pool,refining the grain size of the weld,and promoting the precipitation of theβphase in the weld can be achieved by virtue of the oscillating laser beam stirring the molten pool.As the oscillation frequency increases from 0 to 100 Hz,the area fraction ofβphase in the weld increases from 3.37%to 12.3%,whereas the weld porosity decreases from 5.02%to 0.2%.Conclusions Oscillating laser beam stirs the molten pool to facilitate heat transfer and reduce the temperature gradient of the molten pool.The stirring of the molten pool caused by the oscillating laser beam drives the fluid to flow in the same direction and forms vortices,which thereby increase the stability of the molten pool and result in a sound weld.Oscillating laser welding refines the grain size of the weld and hence increases the amount of grain boundary by stirring the molten pool,thereby promoting the precipitation ofβphase in the weld.The molten pool created by oscillating laser welding is wide and shallow compared with that created via conventional laser welding;thus,the gas bubbles in the former have sufficient time to leave the molten pool,which reduces the gas porosity.Meanwhile,the stirring effect of the oscillating laser beam on the molten pool helps gas bubbles escape from the molten pool surface,which contributes to the reduction in weld porosity.
作者
石铭霄
肖艳
孙贺昱
王伟华
陈九公
杨晓杰
Shi Mingxiao;Xiao Yan;Sun Heyu;Wang Weihua;Chen Jiugong;Yang Xiaojie(School of Materials Science and Engineering,Jiangsu University of Science and Technology,Zhenjiang 212003,Jiangsu,China;China Special Equipment Inspection and Research Institute,Beijing 100029,China;Guangdong Welltech Technology Co.,Ltd.,Zhongshan 528437,Guangdong,China)
出处
《中国激光》
北大核心
2025年第12期43-52,共10页
Chinese Journal of Lasers
基金
江苏省高校自然科学基金(22KJA460011)。
关键词
铝合金
振荡激光焊接
熔池流体的流动行为
焊接温度场
流场
aluminum alloy
oscillating laser welding
flow behavior of the molten pool fluid
welding temperature field
velocity field
