铌在堆焊金属中的应用

Applying of Niobium in Surfacing Weld Metals

利用X射线衍射、TEM、EPMA、SEM等研究了含Nb堆焊金属中的碳化物分布形态及基体组织,分析了碳化物形成过程。结果表明,Nb的加入有利于形成大量碳化物硬质相,但Nb含量过多时,会形成铁素体基体及大量共晶碳化物,导致堆焊金属硬度过低;适量Ti、Nb、V共同作用时,能获得大量均匀分布的颗粒碳化物及马氏体或贝氏体基体,颗粒碳化物是以氧化物为核心的复合碳化物,内层Ti含量高于Nb,外层Nb含量高于Ti。

Microstructure of Nb alloyed surfacing weld metals are investigated by means of X-ray diffraction, TEM, SEM and EPMA. And the precipitating processes of carbides are discussed. It indicates that alloying of Nb into weld metals can promote the precipitation of carbides. But too much Nb can resulte in the formation of eutectic carbides and ferrite matrix, which can decrease the hardness of weld metals. Coexisting of appropriate amount of Nb, Ti and V in the weld metals can induce the carbide granules precipitate evenly and matrix microstructure transform to martensite or bainite. The core of the carbides is oxide, and the inner of the carbides contained more Ti than Nb , while more Nb than Ti in the exterior of the carbides.