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目的在Fe-x Cr-3.5B-0.1C药芯焊丝中加入不同含量的铬,了解铬含量对堆焊合金硼化物形貌以及耐磨性能的影响。方法采用CO_2气体保护堆焊的方法在Q235钢基板上制备Fe-Cr-B系耐磨合金,利用光学显微镜、XRD、SEM等方法观察堆焊合金层的显微组织结构,以及湿砂橡胶轮磨粒磨损试验机对堆焊层进行磨粒磨损试验。结果堆焊合金层主要由铁素体枝晶、马氏体、珠光体和硼化物组成,硼化物随着Cr含量的增加发生Fe_2B到M_2B(M=Fe,Cr)的转变,它主要分布在金属基体的连续网状和鱼骨状结构中。凝固过程中,当Cr质量分数大于9%时,首先形成初生M_2B颗粒,随后形成共晶的M_2B和BCC结构的Fe基固溶体,这种共晶的微观结构主要由基体和长条状的M_2B硼化物组成。从Cr与(Fe,Cr)的原子数分数比值可以看出,硼化物发生从Fe_2B→(Fe,Cr)_2B→(Cr,Fe)_2B的转变。铬含量对Fe-Cr-B系耐磨堆焊合金的组织、硼化物形貌有较大影响。由于硼化物空间结构的变化,硼化物的显微硬度会随着铬原子进入Fe_2B而逐渐提高。结论随Cr含量的增加,及共晶硼化物硬质相的析出,堆焊合金的硬度和耐磨性呈现持续提高的趋势。当Cr含量为20%时,合金中生成的长条状M_2B相作为耐磨骨架无序的分布且镶嵌于基体中,合金耐磨料的磨损性能比Cr含量为9%时的提高了约7.4倍。
Aim To investigate the effect of chromium content on the morphology and wear resistance of boride alloy in Fe-x Cr-3.5B-0.1C flux-cored wire with different content of chromium. Methods Fe-Cr-B wear-resistant alloy was prepared on Q235 steel substrate by CO_2 gas shield surfacing method. The microstructure of the surfacing alloy layer was observed by optical microscope, XRD and SEM. Abrasive wear testing machine wear layer wear test. Results The surfacing alloy layer was mainly composed of ferrite dendrite, martensite, pearlite and boride. The borides changed from Fe 2 B to M 2 B (M = Fe, Cr) with the increase of Cr content. Metal matrix in a continuous network and fishbone structure. When the mass fraction of Cr is more than 9%, the primary M_2B particles are firstly formed and then the Fe-based solid solution of the eutectic M_2B and BCC structures is formed. The microstructure of this eutectic mainly consists of the matrix and the elongated M_2B boron Chemical composition. From the atomic ratio of Cr and (Fe, Cr), it can be seen that the borides change from Fe_2B → (Fe, Cr) _2B → (Cr, Fe) _2B. Chromium content of Fe-Cr-B wear-resistant surfacing alloy microstructure, boride morphology has a greater impact. Due to the change of the spatial structure of borides, the microhardness of borides gradually increases with the entry of chromium atoms into Fe_2B. Conclusion With the increase of Cr content and the precipitation of eutectic boride hard phase, the hardness and wear resistance of the surfacing alloy tend to increase continuously. When the content of Cr is 20%, the elongated M_2B phase formed in the alloy is disordered as wear-resisting skeleton and embedded in the matrix. The wear resistance of the wear-resistant alloy increases by about 7.4 compared with that of Cr content of 9% Times