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采用光学显微镜(OM)、扫描电镜(SEM)观察以及相图计算、拉伸试验、硬度试验,分析了Nb对三组690镍基合金焊条熔敷金属组织与性能的影响。结果表明:熔敷金属中的Nb以碳化物MC(M=Nb,Ti)相的形式析出。随着Nb含量的增加,熔敷金属中奥氏体晶粒的长大受到抑制,晶粒变细,晶界面积增大;随着Nb含量的增加,熔敷金属中的MC析出相增加,M_(23)C_6(M=Cr,Fe)析出相减少,晶界变得更加曲折,高温低塑性裂纹敏感性降低;随着Nb含量的增加,熔敷金属的硬度值和塑性提高。
The effects of Nb on the microstructure and properties of the deposited metal of three groups of 690 Ni-based alloy electrodes were analyzed by optical microscope (OM), scanning electron microscope (SEM) and phase diagram calculation, tensile test and hardness test. The results show that Nb in the deposited metal is precipitated as carbide MC (M = Nb, Ti) phase. With the increase of Nb content, the growth of austenite grains in the deposited metal is inhibited, the grains become thinner and the grain boundary area increases. With the increase of Nb content, the precipitated phase of MC increases, The precipitation of M_ (23) C_6 (M = Cr, Fe) decreases, the grain boundaries become more tortuous, and the sensitivity of high temperature low plastic deformation decreases. With the increase of Nb content, the hardness and plasticity of the deposited metal increase.