【摘要】 42CrMo合金钢C含量高、合金元素含量多、淬硬倾向大,焊接性能差。激光焊接具有功率密度高、焊接变形小等优点,适合焊接传统工艺难焊的同种或异种金属。通过额定功率为3kW的Nd∶YAG固体激光器焊接42CrMo,采用光学显微镜(OM)、扫描电镜(SEM)、X衍射、硬度仪分析了焊缝区域组织、成分和硬度变化。研究结果表明:焊缝区域组织为马氏体,热影响完全淬火区的组织为马氏体+贝氏体组织,热影响不完全淬火区的组织为贝氏体。从焊缝正面到焊缝背面的硬度分布表明:由于焊缝正面有保护气体的作用提高了焊缝正面熔池的冷却速度,使焊缝背面的硬度低于焊缝正面的硬度。更多还原

【Abstract】 It was difficulty to weld alloy steel 42CrMo for its high contents of carbon and diverse element. Laser welding was a high energy-density, low heat-input process with specific advantages over conventional fusion welding processes. These included high welding speed, narrow heat-affected zone and low distortion. Laser welding had distinct advantage over conventional fusion welding processes. Exploring experiments of laser welding alloy steel 42CrMo were conducted. Microstructure of the welded seam was characterized by optical microscopy ( OM) , scanning electron microscopy (SEM) and X-ray diffraction (XRD) . Mechanical properties of the welded seam were evaluated by microhardness. The results showed that microstructure of welded seam was martensite. Completly quench region was martensite and bainite. Local quench region was bainite. Microhardness of the welded seam on bottom surface was lower than that of top surface due to protective gas effect.更多还原