不同焊补工艺对E260-450-MS铸钢件焊接组织及性能的影响

Effect of Different Welding Repair Processes on Microstructure and Properties of E260-450-MS Cast Steel

铸钢件的焊补效果关系到转向架构件的服役寿命,为确定合适的焊补工艺,本研究采用3种不同焊补工艺对E260-450-MS铸钢件焊接接头的金相组织、拉伸性能、硬度、冲击性能进行了对比研究。结果表明:3种不同焊补工艺的接头焊缝、热影响区和母材的金相组织无明显的差异;接头抗拉强度均高于450 MPa,断后伸长率均超过20%,断裂部位均位于母材;接头硬度分布规律一致,从母材到焊缝中心,维氏硬度值先升高后降低,硬度峰值均小于250HV3。焊接接头各区冲击吸收能量值大小关系为:焊缝>热影响区>母材,焊缝冲击断口为韧窝断口,热影响区和母材为解理断口。焊前不预热,焊后保温覆盖缓冷,且不进行热处理的焊补工艺为最优焊补工艺。

The welding repair effect of cast steels is related to the service life of bogie components.In order to determine the appropriate welding repair process,the metallographic structures,tensile properties,hardness and impact properties of the repair welded joints of E260-450-MS cast steel obtained by using three different weld repairing processes are compared.The results show that there is no obvious difference in the microstructures of the weld seam,heat affected zone and base metal among the joints by the three processes.The tensile strengths of the joints are all higher than 450 MPa,the elongations after fracture are more than 20%,and the fractures are all located in the base metal.The distribution of the joint hardness is consistent.From the base metal to the center of the weld,the Vickers hardness value increases first and then decreases,and the peak hardness of the three kinds of joints are less than 250HV3.The impact absorption energy of the weld seam is the highest,that of the heat affected zone lower,and that of the base metal the lowest.The impact fracture of the weld seam is dimple fracture,and those of the heat affected zone and base metal are cleavage fracture.The optimal welding repair process is no preheating before welding,heat-insulating and slow cooling after welding with no heat treatment.