以2 mm厚7075-T6铝合金薄板为研究对象, 建立了低频余弦振荡扫描激光焊接传热模型, 通过数值模拟得到其焊接温度场。对比研究了焊接工艺参数对传统激光焊接和低频振荡扫描激光焊接温度场的影响规律。研究结果表明, 传统激光焊接温度场呈完全对称分布, 焊接温度呈现连续上升规律; 而低频振荡扫描激光焊接温度场则为不对称分布, 焊接温度则呈现波动上升规律; 在相同的激光功率和焊接速度下, 前者的熔池最高温度及升温速率显著大于后者。在低频振荡扫描激光焊接中, 升温速率随振荡频率和振幅的增大而降低; 熔池最高温度随振幅的增大而降低, 熔池宽度则随振幅的增大而增大。

A heat transfer model for low-frequency oscillation laser welding of 7075-T6 aluminum alloy was established. Then, the welding temperature field was obtained by means of numerical simulation. The effects of such welding parameters as laser oscillation frequency, oscillation amplitude, laser power and welding speed on the temperature fields both for conventional laser welding and for oscillation laser welding were studied and compared. The results showed that in conventional laser welding, the temperature field is totally symmetric, the welding temperature rises continuously; however, in oscillation laser welding, the temperature field is asymmetric, and the welding temperature goes up and then down for several times until it reaches the steady state. At the same laser power and welding speed, both the peak melting pool temperature and the heating rate for oscillation laser welding are lower than those for conventional laser welding. In low-frequency oscillation laser welding, the heating rate increases with the increasing of laser oscillation frequency and oscillation amplitude. As oscillation amplitude increases, the peak melting pool temperature decreases, and the width of the melting pool increases.