冷焊焊缝中的碳化物研究

Study on the carbides in cold-welding surfacing metals

利用SEM ,TEM ,EPMA等方法研究了不同合金系统的冷焊焊缝中碳化物的分布、形态 ,分析了碳化物在冷焊条件下的形成过程 .结果表明 ,Nb、Ti碳化物倾向大 ,可以在液态金属中形成碳化物 ,但单独加入且含量较高时 ,碳化物尺寸过大 ,分布不均匀 ,对基体固溶强化较弱 ;单独加入V时形成了网状碳化物 ;适量Nb ,Ti ,V同时加入 ,获得了均匀分布的颗粒碳化物及强韧的基体 ,碳化物以液态金属中氧化物为形核核心 。

SEM, TEM and EPMA were employed to study th e distribution and morpholog y of carbides in a series of cold-welding weld metals, and then the forming mec hanis m of carbides was proposed. Nb and Ti could combine with C to form carbides in l i quid weld metal due to their strong carbide-forming tendency, but too much Nb o r Ti alone resulted in coarse carbides and poor strengthened matrixes. V induced the carbides precipitate along grain boundary and resulted in hard and brittle matrix. When suitable amount of Nb, Ti and V coexisted in weld metals, both uni formly distributed particulate carbides and well strengthened matrixes were achi eved. The carbides took the oxides in liquid weld metals as nucleus, then transf ormed into multi-layer complex carbide particles by epitaxial growth.