中文摘要：

采用电磁控制CO2焊接工艺在Q235低碳钢板上进行表面堆焊功能层的实验．通过对堆焊功能层进行SEM分析、硬度测量、耐磨性能和热机械性能测试，研究了外加磁场对CO2堆焊功能层的微观组织、硬度、耐磨性和热强硬性的影响规律．结果表明：在外加脉冲交变纵向磁场作用下，堆焊功能层界面结构得到改善、微观组织被明显细化，表面硬度和耐磨性有明显的提高，堆焊功能层具有良好的热强硬性能．

英文摘要：

Functional gradient materials have been applied in many engineering fields,such as hot forging moulds.The CO2 surfacing welding technology is an important technique to fabricate functional gradient materials.The CO2 surfacing welding experiment on Q235 low carbon steel plate has been carried out with additional pulsed AC longitudinal magnetic field（electromagnetic stir,EMS）.Through the analysis of microstructure,hardness,wear resistance and thermal mechanical properties of surface clad layers,the effects and functions of EMS have been studied at CO_2 welded joints.The results show that EMS can improve the interficial microstructure of surface clad layers,refine their grains,increase the hardness and wear resistance of surface layers,and enhance their thermal mechanical properties. This surfacing welding can be applied to fabricate new high quality double metal hot forging moulds and heat stretch extension moulds.