高强度镀锌钢的CO2激光焊接

利用CO2激光对汽车车身用1.5 mm厚高强度双面镀锌钢进行了大量的焊接实验,对焊缝组织进行了显微组织分析和相关的机械性能实验。从理论上推导了在一定焊接工艺条件下,稳定深熔焊接的下临界功率与焊接速度及焦点位置的关系。在同轴和侧吹保护气体的条件下,通过工艺参数优化,激光深熔焊接可以有效地避免高强度镀锌钢热影响区(HAZ)的软化现象以及焊缝气孔的有效控制。锌不稳定的急剧气化,使热影响区扩大和焊接稳定性降低,聚焦镜的保护难度加大,采取了有效措施加以控制。实验结果表明,用氮气作为保护气体,在激光功率1300 W,焊接速度0.8~1.1 m/min,焦点位置在工件表面下0.4 mm处时,得到了满意的焊接质量。焊缝的硬度接近母材硬度的2倍。

CO2 Laser Welding of Zinc Coated High Strength Steel

Based on many experiments of CO2 laser welding of 1.5 mm zinc coated high strength steel to vehicle body, joint microstructure and stress-strain curve of specimen are acquired. Given special welding technology, theoretical Pc-v curve and Pc-Δf curve of stable deep penetration laser welding are deduced. The unstable sharply gasification of zinc enlarges heat-affected zone (HAZ), debases welding stability and increases the difficulty of protecting condenser. Through optimizing technology parameter, adopting coaxial and side blown protective gas, deep penetration laser welding can effectively avoid softening HAZ of welding of zinc coated high strength steel and can control the gas hole. The experimental result indicates that the content welding quality can be gained on the condition of using N2 as protective gas ,the laser power at 1300 W, the welding speed at 0.8～1.1 m/min and defocusing amount at Δf=-0.4 mm, the hardness of welding seam is twice as that of base material.