铬含量对Fe-Cr-B堆焊合金显微组织及耐磨性的影响

发布时间：2019-04-12 08:19

【摘要】：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。
[Abstract]:Aim to investigate the effect of chromium content on the morphology of boride and wear resistance of surfacing alloy by adding chromium in Fe-x Cr-3.5B-0.1C flux-cored wire. Methods Fe-Cr-B series wear resistant alloy was prepared on Q235 steel substrate by CO_2 gas shielded surfacing. The microstructure of the surfacing alloy layer was observed by optical microscope and XRD,SEM. The abrasive wear test of the surfacing layer was carried out on the wet sand rubber wheel abrasive wear tester. Results the alloy layer was mainly composed of ferrite dendrite, martensite, pearlite and boride. With the increase of Cr content, the boride changed from Fe_2B to Mx2B (MxFe, Cr), and the alloy layer was composed of ferrite dendrite, martensite, pearlite and boride. It is mainly distributed in the continuous reticulation and fish-bone structure of the metal matrix. In the solidification process, when the mass fraction of Cr is more than 9%, the primary M _ 2B particles are formed, and then eutectic M _ x _ 2B and Fe-based solid solutions with BCC structure are formed. The microstructure of the eutectic is mainly composed of a matrix and a strip-like M _ 2O _ 2 B boride. It can be seen from the atomic fraction ratio of Cr to (Fe,Cr) that boride is transformed from Fe_2B (Fe,Cr) _ 2B (Cr,Fe) _ 2B. Chromium content has a great influence on the microstructure and boride morphology of Fe-Cr-B system wear-resistant surfacing alloy. Due to the change of boride space structure, the microhardness of boride increases gradually with chromium atom entering Fe_2B. Conclusion with the increase of Cr content and the precipitation of eutectic boride hard phase, the hardness and wear resistance of surfacing alloy continue to improve. When the content of Cr is 20%, the wear resistance of the alloy is about 7.4 times higher than that of the alloy with 9% Cr, and the long-strip Mx2B phase formed in the alloy is disorderly distributed as a wear-resistant framework and embedded in the matrix, and the wear resistance of the alloy is about 7.4 times higher than that of the alloy with 9% Cr content.
【作者单位】：北京工业大学材料科学与工程学院;北京市生态环境材料及其评价工程技术研究中心;
【分类号】：TG455

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