Cr3C2粒径对等离子堆焊铁基合金层组织与耐磨性能的影响

Effect of Cr3C2 Grain Size on the Microstructure and Wear Performance of Fe-based Alloy Plasma Transferred Arc Surfacing

中文关键词: Cr₃C₂ 颗粒尺寸 等离子堆焊 Fe50合金 显微组织 耐磨性能

英文关键词: Cr₃C₂, grain size, plasma surfacing, Fe50 alloy, microstructure, wear resistance

中文摘要:

      在低碳钢表面利用等离子堆焊技术分别制备Fe50堆焊层及添加40％(质量分数)微米和纳米Cr₃C₂的(Fe50+40%微米/纳米Cr₃C₂)复合堆焊层,比较研究添加不同粒径的Cr₃C₂对Fe50合金堆焊层的显微组织与磨损性能的影响。采用X射线衍射仪(XRD)分析堆焊层的相组成,利用扫描电镜(SEM)和能谱分析仪(EDS)观察堆焊层的显微组织形貌及微区成分,通过显微硬度计测试了堆焊层的硬度分布,使用滑动磨损及冲击磨损试验机分别考察了复合堆焊层的磨损性能。结果表明:Fe50等离子堆焊层组织主要由柱状晶α-Fe及其间的网状共晶α-Fe+Cr₂₃C₆组成；而Fe+40%微米/纳米Cr₃C₂堆焊层凝固方式为过共晶,由大量的先共晶碳化物及其间细密、均匀的枝晶与共晶组织组成,并增加了γ-Fe、Cr₇C₃和未熔Cr₃C₂等相；但Fe+40%纳米Cr₃C₂涂层比Fe+40%微米Cr₃C₂涂层析出更多且细小、致密的先共晶碳化物。与Fe50等离子堆焊涂层相比,Fe+40%微米Cr₃C₂涂层的显微硬度、滑动磨损性能及冲击磨损性能分别提高了21%、1.5倍和0.8倍；而Fe+40%纳米Cr₃C₂涂层的显微硬度、滑动磨损性能及冲击磨损性能则分别提高了34.1%、2.4倍和1.7倍,表面的犁沟和剥落及塑性变形明显减少,耐磨性能显著提高。因此,添加纳米Cr₃C₂颗粒可以显著细化铁基合金等离子堆焊层的显微组织并提升其耐磨性能。

英文摘要:

      Plasma surfacing with Fe50 and composite plasma surfacing with 40% (mass fraction) micron and nano Cr₃C₂ (Fe50+40% micro/nano Cr₃C₂) were prepared by plasma surfacing on low carbon steel surface. Effect of Cr₃C₂ with different dia-meter on microstructure and wear properties of Fe50 alloy plasma surfacing were comparatively studied. The phase composition of the plasma surfacing was analyzed by X-ray diffractometry (XRD), the microstructure and micro-area composition observed by scanning electron microscopy (SEM) and energy depressive spectroscopy (EDS), the hardness distribution tested by microhardness tester, and the wear performance investigated respectively by a sliding wear tester and impact wear tester. The results indicate that the microstructure of Fe50 plasma surfacing is mainly composed of columnar crystal α-Fe and its network eutectic α-Fe+Cr₂₃C₆. The solidification mode of Fe+40% micro/nano Cr₃C₂ plasma surfacing is hypereutectic, which is composed of a large number of pre-eutectic carbides and fine and uniform dendrites and eutectic structures among them, with additional phases such as γ-Fe, Cr₇C₃ and unmel-ted Cr₃C₂ ; however, the Fe+40% nano-Cr₃C₂ coating precipitates more than the pre-eutectic carbide of Fe+40% micron Cr₃C₂ coating,which is, furthermore finer, and denser. Compared with Fe50 plasma surfacing coating, the microhardness, sliding wear performance and impact wear performance of Fe+40% micron Cr₃C₂ coating were increased by 21%, 1.5 times and 0.8 times, respectively; whereas the performances of Fe+40% nano Cr₃C₂ coating were increased by 34.1%, 2.4 times and 1.7 times respectively,whose furrow, spalling and plastic deformation were significantly reduced, while the wear resistance notably improved.