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Chin. J. Process Eng. ›› 2020, Vol. 20 ›› Issue (10): 1227-1233.DOI: 10.12034/j.issn.1009-606X.219359

• Materials Engineering • Previous Articles     Next Articles

Effect of nano-Nb addition on microstructure and wear resistance of Fe-based alloy coatings by plasma transferred arc welding

Lulu XU1,2, Wenxu ZHANG1,2, Longsheng ZHAN1, Mingxi LI1,3*   

  1. 1. School of Materials Science and Engineering, Anhui University of Technology, Ma?anshan, Anhui 243000, China 2. Research Center of Modern Surface and Interface Engineering, Anhui University of Technology, Ma?anshan, Anhui 243000, China 3. Key Laboratory of Green Fabrication and Surface Technology of Advanced Metal Materials, Ministry of Education, Anhui University of Technology, Ma?anshan, Anhui 243000, China
  • Received:2019-11-28 Revised:2020-02-11 Online:2020-10-22 Published:2020-10-16
  • Contact: Ming-Xi LI limingxi@ahut.edu.cn

纳米Nb粉对等离子弧喷焊铁基合金组织与耐磨性的影响

徐露露1,2， 张文旭1,2， 詹龙胜1， 李明喜1,3*   

  1. 1. 安徽工业大学材料科学与工程学院，安徽 马鞍山 243000 2. 安徽工业大学现代表界面工程研究中心，安徽 马鞍山 243000 3. 安徽工业大学先进金属材料绿色制备与表面技术教育部重点实验室, 安徽 马鞍山 243000
  • 通讯作者: 李明喜 limingxi@ahut.edu.cn

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Abstract: Plasma transferred arc welding is a kind of surface modification technology. Plasma transferred arc is used as a heat source and alloy powder is sprayed on the surface of metal materials to prepare a wear-resistant coating with excellent performance. In order to further improve the wear resistance of Fe-based alloy, hard particles are often used as the reinforcements of composite materials. At present, there are few researches on in-situ formed NbC reinforcements in Fe-based alloy coatings, and the density of NbC is very close to that of Fe-based alloy, which can be very evenly distributed in the coatings. In this work, Fe-based alloy coatings without nano-Nb and with mass fraction of 1wt%, 3wt% and 5wt% nano-Nb powder were prepared on Q235 surface by plasma transferred arc welding. The phase composition, microstructure, microanalysis and worn surface observation of the coatings were investigated by means of optical microscope (OM), scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and X-ray diffraction (XRD), respectively. The microhardness and wear resistance of the coatings were tested using microhardness tester and pin-on-disc wear machine. The results showed that the main phases of Fe-based alloy coatings were composed of α-Fe, γ-Fe and Cr7C3. NbC phase was identified in the coating by adding nano-Nb powder, and Cr23C6 phase appeared with addition of 5wt% nano-Nb. The untransformed γ-Fe increased and the microstructure changed from approximately equiaxed microstructure to dendrite with addition of nano powder, and the greatly refined microstructure was obtained by adding 5wt% additive. The microhardness of coatings was improved, which was about 766 HV0.3 increased by about 250 HV0.3 with 1wt% and 3wt% nano-Nb. The wear resistance of coatings was also improved. The minimum friction coefficient of 0.48 was obtained by adding 3wt% nano-Nb. The wear mechanism changed from adhesive wear to abrasive wear.

Key words: plasma transferred arc welding, Fe-base alloy, nano-Nb powder, microstructure, wear resistance

摘要： 采用等离子弧喷焊技术在Q235表面制备未添加与分别添加1wt%, 3wt%和5wt%纳米Nb粉的铁基合金喷焊层。通过X射线衍射仪(XRD)、金相显微镜(OM)、扫描电镜(SEM)和能谱仪(EDS)对喷焊层的相组成、显微组织、微区成分及磨损形貌进行分析；利用维氏硬度仪和销盘磨损仪检测喷焊层截面硬度和表面耐磨性。结果表明，铁基喷焊层主要由α-Fe, γ-Fe和Cr7C3组成，添加纳米Nb粉后原位生成NbC相，且随Nb含量增至5wt%，出现了Cr23C6相。纳米Nb粉的加入使喷焊层组织中未转变的奥氏体增多，组织形貌由近等轴晶转变为树枝晶，并且添加5wt%纳米Nb粉的喷焊层组织发生明显细化。添加纳米Nb粉使喷焊层的硬度明显提高，其中添加1wt%和3wt%纳米Nb粉的喷焊层硬度均可达约766 HV0.3。纳米Nb粉的加入同时提高了喷焊层的耐磨性，磨损机制由黏着磨损变为磨粒磨损。

关键词: 等离子喷焊, 铁基合金, 纳米Nb, 组织, 耐磨性