Iron-based alloy overlays are widely utilized in industry to extend the service life of components subjected to wear and corrosion attack. Welding is an overlay process commonly employed because of its low cost and high efficiency. The microstructure of an as-welded chromium carbide overlay and a new Fe-Cr-C-B overlay containing multiple alloying elements has been characterized by optical microscopy, scanning electron microscopy, X-ray diffraction, and electron backscatter diffraction (EBSD). The microstructure of the chromium carbide overlay consists of large $$\hbox {M}_7\hbox {X}_3$$ M 7 X 3 primary carbides and austenite and carbide eutectic phases. The microstructure of the new overlay consists of granular MX-type primary carbide ( M = Nb, Ti, Mo; X = C and B), dendritic $$\delta $$ δ -ferrite/austenite, eutectic phases of austenite and $$\hbox {M}_2\hbox {B}$$ M 2 B boride ( M = Fe and Cr). The austenite portion of the microstructure has been subsequently transformed into martensite and retained austenite. The fine MX-type hard particles and refined eutectic and matrix microstructure lead to the high hardness of the overlay. The non-equilibrium solidification process for the complex microstructure is discussed using ThermoCalc.

中文翻译：

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耐磨 Fe-Cr-CB 覆盖层的凝固组织

铁基合金覆盖层在工业中被广泛使用，以延长遭受磨损和腐蚀攻击的部件的使用寿命。焊接是一种常用的覆盖工艺，因为它成本低、效率高。焊态碳化铬堆焊层和含有多种合金元素的新型 Fe-Cr-CB 堆焊层的微观结构已通过光学显微镜、扫描电子显微镜、X 射线衍射和电子背散射衍射 (EBSD) 进行表征。碳化铬覆盖层的微观结构由大 $$\hbox {M}_7\hbox {X}_3$$ M 7 X 3 初级碳化物和奥氏体和碳化物共晶相组成。新堆焊层的微观结构由粒状 MX 型初生碳化物（M = Nb、Ti、Mo；X = C 和 B）、枝晶 $$\delta $$ δ -铁素体/奥氏体组成，奥氏体和 $$\hbox {M}_2\hbox {B}$$ M 2 B 硼化物（M = Fe 和 Cr）的共晶相。显微组织的奥氏体部分随后转变为马氏体和残余奥氏体。细小的MX型硬质颗粒和细化的共晶和基体微观结构导致堆焊层硬度高。使用 ThermoCalc 讨论了复杂微观结构的非平衡凝固过程。