| The Fe-based alloy coating(Fe50), Fe50+Cr3C2, Fe50+Ti, Fe50+Cr3C2+1%Ti composite coatings on Q890steel substrate produced by plasma transferred arc weld-surfacing process were studied in this paper. Microstructure and constituent phases of the coatings were investigated by means of optical microscope(OM), scanning electron microscope(SEM),EDS and X-ray diffraction instrument(XRD). The micro-hardness,wear resistance and electrochemical corrosion of the coatings were also tested. Compared with Fe50, Fe+Cr3C2and Fe+Ti coating, the effect of complex addition of Ti and Cr3C2on microstructure and properties of Fe-based alloy coating produced by plasma transferred arc weld-surfacing process were mainly discussed.It was found that the main phases of the Fe55coating were a-Fe and Cr23C6. The Fe50+Ti coatings were composed of a-Fe, γ-Fe and Cr23C6.The Fe50+Cr3C2composite coatings were composed of y-Fe,a-Fe,Cr23C6and Cr3C2,When the content of Cr3C2added to30%,there exixts Cr7C3.Besides γ-Fe,a-Fe and Cr23C6,Cr7C3and Cr3C2alse exixted in the Fe50+Cr3C2+1%Ti coatings, with the increase of the content of added Ti,the composite coating appears TiC phase.The Fe50coating consisted of developed a-Fe dendrite and fine eutectic structure (a-Fe+Cr23C6).The microstructure of Fe50coating was largerly changed by adding Ti particles,and the microstructure of Fe50+Ti tranferred to equiaxed grains. The micro-hardness and wear resistance of Fe50+1%Ti coating were greatly improved,but with the increase of the content of Ti, the micro-hardness and wear resistance of the coating get worse. The corrosion current of Fe50+Ti layer reduced by an order of magnitude, indicating that the corrosion resistance of Fe50+Ti series composite coating were geeatly improved.The microstructure of all composite coatings was greatly refined by adding Cr3C2particles. There was a few undissolved Cr3C2existing in the Fe+Cr3C2composite coatings. The Fe50+10%Cr3C2and Fe50+20%Cr3C2composite coatings mainly consisted of fine dendrite and eutectic structure. Fe50+30%Cr3C2composite coatings mainly consisted of eutectic structure. Vast scale primary carbides and fine dendrite and eutectic structure were observed in the Fe50+40%Cr3C2,Fe50+50%Cr3C2composite coating. The micro hardness and sliding wear resistance of the Fe+Cr3C2composite coatings were obviously better than that of Fe50alloy coating.Compared with Fe50+Cr3C2composite coatings,the dendrite tissue of Fe50+20%Cr3C2+1%Ti obviously equiaxed and homogenized. Fe50+30%Cr3C2+1%Ti coating crystallization by hypereutectic way, and its microstructure consists of the short,crushing dendrite solid solution and fine eutectic and the content of the eutectic structure greatly decreased; The number of primary carbides of Fe50+40%Cr3C2+1%Ti coating reduced and distributed more uniform, the dendtites and eutectic structure also get some refinement.Compared with Fe50+Cr3C2composite coatings,the micro-hardness and wear resistance of the Fe50+Cr3C2+Ti coatings were obviously improved. With the addition of different content of Ti,the crystallization style of Fe50+30%Cr3C2coating changed,the microstructure of the coating mainly consisted of distributing-uniformed flower-shaped equiaxed,but with the increase of Ti, the microstructure of the coating becomes larger,the eutectics among the dendtites solid solution reduced and the hardness also decreased, showing that more Ti is not better.It showed that the comprehensive properties of Fe50+30%Cr3C2+1%Ti composite coating were the best. |
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