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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CO_2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 the effect of alloying elemental phosphorus in automotive high strength steel on the quality of laser welding head, a 12kW CO2 laser was used to weld 4.8mm thick phosphorus-free high strength interstitial-free M250P1 steel with high power. The welded joints under different welding parameters were subjected to the forming test, the tensile mechanical properties, the microstructures and the scanning electron microscopy (EDS) spectrum analysis. The results show that although the M250P1 welded joint has good tensile mechanical properties and formability under certain welding parameters, the welded joint is still prone to cracking in the nugget zone during the deformation process. The main reason is that the metal In the rapid cooling, the phosphorus element was too late to spread in the grain boundary aggregation, the formation of phosphorus segregation, resulting in decreased toughness of welded joints.