为了研究汽车用高强钢中合金元素磷对激光焊接头质量的影响，采用12kW的CO2激光器对4.8mm厚的含磷高强度无间隙原子钢M250P1进行了高功率焊接。对不同焊接工艺参量下的焊接接头进行了成型试验、拉伸力学性能、显微组织和扫描电子显微镜能谱分析。结果表明,在特定焊接工艺参量下，M250P1焊接接头虽具有良好的拉伸力学性能和成型性能，但在形变过程中焊接接头仍容易在熔核区发生开裂，其主要原因是熔核区内金属在快速冷却时，磷元素来不及扩散，在晶界聚集，形成磷偏析，导致焊接接头韧性下降。

In order to study effect of phosphor on welding quality of high strength steel, 4.8mm thick P-added high strength interstitial free steel M250P1 was welded with a 12kW CO2 laser. For different welding parameters, different welding nodes were obtained, and their tensile dynamic property, microstructure and scanning electron microscope energy spectrum were observed. The results show that: for given welding parameters, the weld joints show good tensile and forming property, however, crack is prone to happen on the fusion zone because of the toughness reduction induced by phosphorus microsegregation in the fusion zone. The phosphorus element in the fusion zone hadn’t enough time to diffuse and aggregated on the grain boundary when the fusion metal was quickly cooled after weld.