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研制9%Ni钢用镍基焊条的难点在于满足熔敷金属强度和塑性指标的前提下提高其低温韧性。在力学性能分析的基础上,采用彩色金相分析、扫描电镜及能谱分析、X射线衍射分析技术研究了铌对9%Ni钢用镍基焊条熔敷金属组织和性能的影响。试验结果表明,熔敷金属中铌的加入能明显提高其强度和塑性。但铌的质量分数达到3.5%后,虽然熔敷金属的强度进一步提高,但形成了脆性的金属间化合物Laves相,导致熔敷金属低温韧性下降。
The difficulty of developing Ni-based welding electrodes for 9% Ni steel is to improve its low temperature toughness under the premise of meeting the strength and ductility index of deposited metal. Based on the analysis of mechanical properties, the effect of niobium on the microstructure and properties of the deposited metal of 9% Ni steel with Ni-based electrode was studied by means of color metallographic analysis, SEM and EDS and X-ray diffraction analysis. The test results show that the addition of niobium in the deposited metal can obviously improve its strength and ductility. However, when the mass fraction of niobium reaches 3.5%, although the strength of the deposited metal is further increased, the brittle intermetallic Laves phase is formed, resulting in a decrease in the low temperature toughness of the deposited metal.