高频微振条件下激光焊接组织研究

为了研究振动工艺在激光焊接方面的应用,选用工业纯铁为研究对象,进行不同激光焊接参数与振动频率下的高频微振光纤激光焊接,达到优化接头成形,提高焊接质量的目的。利用超景深显微镜观察焊接接头宏观形貌,利用扫描电镜分析接头微观组织,利用显微硬度计测量焊接接头显微硬度分布。结果表明:在高频微振激光焊接中,施加振动可增加焊接接头熔深。焊缝晶粒细化,表现为振动频率越快,晶粒越细小。振动加速度可以作为振幅的替代参量;当振动频率与材料本身固有振动频率相近时,振动加速度越大,晶粒细化作用不明显。当激光功率为3 000 W、离焦量为-10 mm、焊接速度为1.2 m/min、振动频率为118 Hz、振动加速度为36.1 m/s~2时,焊接接头的整体平均显微硬度由无振动条件下的273.3 HV降低到244.6 HV,且组织晶粒细化最明显。

Microstructure Characteristic of Laser Welded Joint under High Frequency Micro-vibration Condition

To study the application of vibratory process on laser welding, the industrial pure iron is selected in this research. Different laser welding parameters and vibratory frequency parameters are carried out to optimize the welding joint forming and to improve the welding quality. The cross-section morphology, microstructure and microhardness of the welding joint are studied by optical microscope, scanning electron microscope and microhardness tester respectively. The results indicate that the depth of fusion is increased by vibration. The grains in weld metal are dramatically refined at a higher vibration frequency. On the other hand, vibration acceleration can be used as an alternative parameter for vibratory amplitude. Under the condition that the applied vibration frequency is close to the inherent vibration frequency of the material, the grain refining effect is not obvious when the vibration acceleration becomes higher. The average value of welding joint microhardness is decreased from 273.3 HV without vibration to 244.6 HV with the parameters of 3 000 W the laser power,?10 mm the defocusing amount, 1.2m/min the welding speed, 118Hz the vibration frequency and 36.1 m/s2the vibration acceleration. At the same time, the conspicuous grain refinement can be observed.