Mn含量对ENiCrMo-2镍基焊条熔敷金属组织和性能的影响

Effect of Mn Content on the Microstructure and Properties of the Deposited Metal of ENiCrMo-2 Welding Electrode

采用焊条电弧焊方法制备了ENiCrMo-2镍基焊条合金熔敷金属。采用光学显微镜(OM)、扫描电子显微镜(SEM)以及能谱分析(EDS)方法对熔敷金属的晶界形貌、析出相成分、析出相形貌特征加以研究;对熔敷金属进行拉伸试验并分析断口形貌,研究了Mn含量对熔敷金属组织及力学性能的影响。结果表明,显微组织以奥氏体柱状晶为主,Mn含量的提高改变了偏析带宽度,但对析出相的影响并不明显。析出相包括富Cr碳化物(M_(7)C_(3))以及富Mo、Cr碳化物(M_(23)C_(6)),部分析出物为M7C3包裹着M_(23)C_(6);随着Mn含量从0.16 wt.%升高到0.91 wt.%,熔敷金属的塑韧性和抗裂性得到提高,熔敷金属力学性能良好。通过断口分析发现,当Mn含量为0.16 wt.%时,存在较弱的结晶裂纹和高温失塑裂纹倾向,Mn含量的提高使裂纹倾向减弱,沿晶开裂的断裂面上的韧窝形貌逐渐均匀变深。因此,适当增加Mn含量可优化ENiCrMo-2镍基焊条合金熔敷金属的组织和力学性能,当Mn含量增加至0.91 wt.%时熔敷金属的力学性能最优。

ENiCrMo-2 nickel-based welding rod alloy cladding metal was prepared using SMAW.The microstructure of the cladding metal was studied by optical microscopy(OM),scanning electron microscopy(SEM),and energy dispersive spectroscopy(EDS)methods.The grain boundary morphology,precipitate phase composition,and precipitate phase morphology characteristics were studied.The tensile test was conducted on the cladding metal,and the fracture morphology was analyzed to study the effect of Mn content on the microstructure and mechanical properties of the cladding metal.The results showed that the microstructure was mainly columnar austenite,and the increase in Mn content changed the width of the segregation zone,but had no significant effect on the precipitate phase.The precipitate phase included Cr-rich carbides(M_(7)C_(3))and Mo-and Cr-rich carbides(M_(23)C_(6)),with partial precipitates being M_(7)C_(3) encapsulated by M_(23)C_(6).With the increase in Mn content from 0.16 wt.%to 0.91 wt.%,the ductility and crack resistance of the cladding metal were improved,and the mechanical properties of the cladding metal were good.Through fracture analysis,it was found that when the Mn content was 0.16 wt.%,there was a weak tendency for crystal cracks and high-temperature ductile cracks.The increase in Mn content weakened the crack tendency,and the dimple morphology on the fractured surface along with grain boundaries became gradually deeper and more uniform.Therefore,appropriately increasing Mn content can optimize the microstructure and mechanical properties of ENiCrMo-2 nickel-based welding rod alloy cladding metal.When the Mn content is increased to 0.91 wt.%,the mechanical properties of the cladding metal are optimal.