| CHEN Xiang,ZHANG Deqiang,LI Jinhua,GUO Haihua,YAO Fangping,PU Ruohua.Effect of Heat Flux on Microstructure and Properties of High-speed Steel Cutter WC/Co Ceramic Layer by Laser Multiple-channel Cladding[J],53(13):207-219 |
| Effect of Heat Flux on Microstructure and Properties of High-speed Steel Cutter WC/Co Ceramic Layer by Laser Multiple-channel Cladding |
| Received:April 22, 2023 Revised:October 09, 2023 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2024.13.020 |
| KeyWord:laser cladding heat flux WC/Co ceramic cladding microstructure high-speed steel cutter multi-channel cladding |
| Author | Institution |
| CHEN Xiang |
Engineering Training Center,Liaoning Jinzhou , China |
| ZHANG Deqiang |
School of Mechanical Engineering and Automation, Liaoning University of Technology, Liaoning Jinzhou , China |
| LI Jinhua |
School of Mechanical Engineering and Automation, Liaoning University of Technology, Liaoning Jinzhou , China |
| GUO Haihua |
School of Mechanical Engineering and Automation, Liaoning University of Technology, Liaoning Jinzhou , China |
| YAO Fangping |
School of Mechanical Engineering and Automation, Liaoning University of Technology, Liaoning Jinzhou , China |
| PU Ruohua |
Training Center, Dalian Economic and Trade School, Liaoning Dalian , China |
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| Abstract: |
| It is an advanced technology of surface modification, repair and remanufacturing by laser cladding, which has an incomparable advantage over traditional cutter repair methods in surface modification and damage remanufacturing of cutting tools. Cermet powder can effectively increase the hardness of cladding layer, so that it can meet the basic hardness requirements of cutter. WC/Co cermet powder is one of the ideal materials for cutter repair. The work aims to study the effect mechanism of the heat flux on the multi-channel cladding layer and the selection of parameters in the preparation of multi-channel cladding layer by laser on multi-channel WC/Co ceramic cladding layer on the surface of high-speed steel cutter. By establishing the theoretical model, the COMSOL Multiphysics was used to conduct simulation analysis on the multi-channel laser cladding process and the temperature field of the multichannel model, and the YLR-3000 fiber laser processing system was adopted to prepare WC/Co single-layer multi-channel ceramic cladding layer on 45 mm×30 mm×10 mm high-speed steel cutter surface by coaxial powder feeding process. The samples were cut by wire cutting and the microstructure of cladding section was observed and analyzed by Axio Vert.A1 inverted metallographic microscope. The microstructure of cladding layer was analyzed by S-3000N scanning electron microscope (SEM) and NORAN-QUEST Ⅱ energy dispersive spectrometer (EDS). The hardness of cladding layer was measured by HVS-1000 microhardness tester. The phase characterization was analyzed by D/MAX-2500 X-ray diffractometer. The multi-factor laser process parameters were coupled and the morphology, structure and properties of cladding layer were analyzed by the heat flux (qn). The correctness of the theoretical model was verified by simulation analysis, and the effect law of heat flux between adjacent channels of single-layer and multi-channel cladding layer was obtained. By the simplified experiment, the effect law of heat flux was found that when the nth cladding layer was prepared, the heat flux of the subsequent n+1 cladding layer was greatly affected, while after that, the effect was less. When the qn was less than 24.06×106 W/m2, the cladding layer usually exhibited pores but few cracks, and the microstructure of the cladding layer was mainly slender dendritic structure. When the qn ranged from 36.09×106 to 39.82×106 W/m2, the cladding layer usually exhibited few pores, and the microstructure was uniform without cracks, forming the polycrystal mixed structure with cellular WC and dendritic W2C as the main strengthening phases. When the qn reached more than 44.11×106 W/m2, the cladding layer usually exhibited more pores and vertical and longitudinal penetrating cracks, and the microstructure was the stable massive WC structure. In the lap zone of cladding layer, the polycrystal mixed structure mainly consisted of cellular and dendritic crystals. In the non-lap zone, the structure mainly consisted of dispersed dendritic crystals. The phase structure of multi-channel ceramic cladding layer was mainly composed of Fe3W3C, Co3W3C, Mo3Co3C, W2C, WC, Cr3Mo, (Cr,Fe)7C3 and a variety of interstitial compounds. The main phases of multi-channel cladding layers with different heat flux are almost the same, but the internal microstructure is closely related to the heat flux in the laser cladding process. With the increase of the heat flux, the microstructure of cladding layer changes from dendritic crystals to cellular crystals, and then gradually forms stable massive crystals. The microhardness values of each position in the cladding layer increase firstly and then decrease gradually with the increase of the heat flux. When the heat flux reaches 36.09×106W/m2, the hardness values of each position in the cladding layer are higher than those at other heat flux, which is an ideal choice of process parameters. Higher heat flux increases the mass of substrate participating in cladding, but reduces the bending strength of substrate and increases the possibility of fracture of cladding layer and substrate. The microstructure between the lap zone and the non-lap zone has a slight difference. The microhardness of the whole cladding layer fluctuates, but the fluctuation has a certain regularity. |
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