690镍基合金焊条熔敷金属的组织与性能研究

采用金相显微镜、扫描电镜、拉伸试验、弯曲试验和晶间腐蚀试验分析了690镍基合金ENiCrFe-7焊条中各元素对熔敷金属组织、缺陷和力学性能的影响，研制符合核电设备使用要求的焊条.研究表明：焊缝熔敷金属中的沿晶裂纹引起焊缝金属拉伸性能、冲击韧性和弯曲性能的降低；随着焊缝中Nb，Ti元素含量的增加，焊缝析出相(Nb，Ti)(C，N)和NbC的数量增加，焊缝中滑移晶界受到析出相的钉扎，裂纹扩展受到抑制，焊缝熔敷金属的强度、塑性和弯曲性能得到提高；Nb和Ti的加入减小了Cr23C6析出数量，抑制了晶间腐蚀裂纹的产生.新研制的镍基焊条满足核电设备对焊缝熔敷金属的性能要求.
In order to develop the welding electrodes and meet the requirement for the key components of nuclear power plant,the influence of ENiCrFe-7 welding electrodes compositionon the microstructure and mechanical properties of Ni-based weldments have been analyzed using optical microscopy, scanning electron microscopy, tensile test, bending test and intergranular corrosion test. The results showed that intergranular cracks caused the degradation of tensile strength, impact energy and bending property of weld metal. The addition of Nb and Ti can form MX (M=Nb,Ti,X=C) precipitates, which were present to “pin” grain boundary motion and impede the propagation of cracks. The precipitates increased with the increase of Nb and Ti contents in the weld metals. The addition of Nb and Ti can improve the tensile strength, plasticity and bending property of the weld metals. The addition of Nb and Ti can fix C in grain, decrease the number of Cr23C6, which is helpful for minimizing intergranular corrosion of the weld. The self-made electrode had good comprehensive property which could meet the requirements for the key components of nuclear power plant.