Microstructure and friction behavior of hard phase in laser cladding Fe-Cr-Co-W alloy

In order to analyze the metallurgical crystallization process of Fe-Cr-Co-W alloy system cladding layer and the micro morphology and formation mechanism of wear-resistant hard phase, and explain the mechanism of improving wear resistance of Fe-Cr-Co-W alloy system cladding layer, Fe-Cr-Co-W alloy powders with different components were cladding on the surface of Q235 steel by laser cladding process, and a certain thickness of cladding layer was obtained. The metallographic structure analysis and phase test of laser cladding layer were carried out. The dry friction comparative experiments of Fe-Cr-Co-W cladding layers with different components were carried out. The microstructure and morphology of cladding layer after dry friction were studied, and the hardness of hard phase was tested. The experimental results show that the microstructure of the cladding layer is dense and fully metallurgical bonded with the matrix structure. The structure of the cladding layer is mainly that the leaf vein hard phase is distributed on the γ-Fe matrix. Combined with the results of scanning electron microscopy, energy spectrum analysis and X-ray diffraction analysis, the vein like hard phase is Co3W3C. In the surface morphology of the cladding layer after dry friction on the M-200 testing machine, the leaf vein like hard phase Co3W3C plays a supporting role on the surface of the cladding layer and floats on the surface of the matrix structure, reducing the wear of the matrix structure and reducing the wear. With the increase of W and Co content, the amount of leaf vein hard phase Co3W3C increases and the friction coefficient decreases. Under the same experimental conditions, the minimum wear loss of Fe-Cr-Co-W cladding layer with different content is 1/60 of Fe-Cr cladding layer.Highlights: Laser cladding technology is used to form the cladding layer on the surface of Q235 steel with Fe-Cr-Co-W alloy powder. The compact structure of the cladding layer shows that the laser cladding process has good performance. The experimental results show that the wear resistance of the cladding layer can be significantly improved by adding W and Co, up to 60 times; The microstructure and formation mechanism of the cladding layer are analyzed and explained. The phase composition and wear-resistant mechanism of the hard phase leaf vein Co3W3C of the cladding layer are found and emphatically analyzed, which provides a theoretical and practical reference for the failure repair and surface strengthening of metal parts by laser technology.