为了研究大功率光纤激光焊在304不锈钢上的焊缝成形,使用5～7 kW的激光功率,10～100 mm/s的焊接速度在16 mm厚的304奥氏体不锈钢上进行全覆盖参数试验。随后观察了焊缝的熔深、熔宽、焊缝形状等成形参数。结果表明,焊接速度低于20 mm/s时,焊缝表面会形成隆起,熔深随速度减慢,迅速增加;焊接速度在30～40 mm/s时,焊缝表面变得凹凸不平且两边存在咬边,熔深随速度减慢且小幅增加;焊接速度介于50 mm/s和90 mm/s之间时,焊缝的熔深和熔宽几乎不变;而当速度达到100 mm/s时,熔深急剧减小,且钉头形焊缝的形状发生了很大的改变。通过以上试验结果结合小孔效应和熔池特性分析了激光焊缝的成形机理,对大功率光纤激光焊接形成了更全面的认识。

A full coverage experiment with 5-7 kW laser power and 10-100 mm/s welding speed are made to study the weld bead formation of high power fiber laser welding on 304 austinite stainless steel. Then, welding formation characteristics such as penetration deepth, weld bead width and shape are observed. The results show that humping occurs and penetration depth increases rapidly when the travel speed is lower than 20 mm/s; weld bead is lower than the initial surface occasionally and undercut occurs when the travel speed is 30-40 mm/s; weld depth and width are almost the same when the travel speeds are among 50-90 mm/s; weld depth decreases suddenly and shape of nail-like weld changes a lot when the travel speed arrives at 100 mm/s. By analysing the results in connection with the keyhole and melt pool characteristics, we have a deeper understanding of the weld formation mechanism and high power fiber laser welding.