Fe-Cr-Nb-B-C金属粉芯丝激光熔覆层的组织与磨损性能

Microstructure and abrasive wear property of Fe-Cr-Nb-B-C alloy deposited by laser cladding with metal powder cored wire

  • 摘要:
    目的 旨在深入分析Fe-Cr-Nb-B-C金属粉芯丝激光熔覆层的物相组成、显微组织及磨粒磨损性能。
    方法 研制了直径为1.2 mm的Fe-Cr-Nb-B-C金属粉芯丝,通过激光送丝熔覆方法在316L不锈钢板上制备了不同B元素含量的铁基熔覆层。通过光学显微镜(Optical microscopy, OM)、硬度计、扫描电子显微镜(Scanning electron microscope, SEM)、X射线衍射仪(X-ray diffractomer, XRD)、能谱仪(Energy dispersive spectroscopy, EDS)和MLS-225型湿式橡胶轮磨粒磨损试验机等手段,对熔覆层中的相组成、组织结构、显微硬度与洛氏硬度、磨粒磨损性能等进行研究。
    结果 结果表明,耐磨熔覆层主要由γ-Fe, NbC, M23(C,B)6以及少量α-Fe组成,其中NbC硬质相会优先形成。在激光送丝熔覆过程中,当熔覆层Nb元素含量约为5.7%,B元素含量为0.9%时,通过外添加碳化硼方式制备的熔覆层综合性能更优、硬度高、耐磨损性能较好。
    结论 随着B元素含量的提高,Fe-Cr-Nb-B-C合金中抗磨粒磨损性能提高,熔覆层中原位生成的NbC和M23(C,B)6硬质相是熔覆层硬度较高、耐磨性较好的主要原因。

     

    Abstract: Objective The aim is to investigate the phase composition, microstructure and abrasive wear property of Fe-Cr-Nb-B-C metal powder core wire laser cladding layer. Methods Fe-Cr-Nb-B-C metal powder cored wire with diameter of 1.2 mm is prepared and iron-based cladding layers with different B contents are then deposited on 316L stainless steel substrates using laser wire feeding cladding techniques. The phase composition of the cladding layer is analyzed by optical microscope (OM), hardness tester, scanning electron microscope (SEM), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and an MLS-225 wet rubber wheel abrasive wear tester. The phase composition, microstructure, microhardness, Rockwell hardness and abrasive wear property of the cladding layer are investigated. Results The results show that the wear-resistant cladding layer primarily consisted of γ-Fe, NbC, M23(C,B)6 and a small amount of α-Fe, with the NbC hard phases forming preferentially. During laser wire cladding, when the Nb element content of the cladding layer is about 5.7% and the B element content is 0.9%, the addition of boron carbide led to optimal cladding layer property, characterized by high hardness and superior wear resistance. Conclusion As the B element content increases, the abrasive wear resistance of Fe-Cr-Nb-B-C alloy cladding layers improved significantly. The in-situ generated NbC and M23(C,B)6 hard phases within the cladding layer is identified as the primary reasons for the enhanced hardness and wear resistance.

     

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