Effect Of Carbon Content On Microstructure And Properties Of FeCrNiMoSiC Laser Cladding Layer

In production practice,the number of workpieces with steel as the main material is huge,and the workpieces will face failure when used for a long time.Iron-based alloy powder is widely used in laser cladding for repairing workpieces because it is similar to steel-based workpieces.Cr,Ni,Mo,Si,and C are common laser cladding iron-based powder addition elements.The addition of alloying elements can directly affect the properties of the cladding layer.C has a great influence on the properties of iron-based alloys.Appropriate carbon content can not only improve the wear resistance of the cladding layer,but also increase the strength.Carbon content exceeds a certain range,the corrosion resistance of the cladding layer will rapidly decrease,so it is necessary to find a suitable C content to improve the overall performance of the cladding layer.The difference in performance is reflected in the microstructure of the cladding layer,and by studying the changes in the structure and phase,it is a microscopic interpretation of performance.Therefore,it is of great significance to study the microstructure of the FeCrNiMoSiC iron-based alloy cladding layer and to repair the steel-based failure workpieces.In this paper,a well-formed cladding layer was prepared by laser cladding technology with different carbon contents FeCrNiMoSiC iron-based powder under the same process parameters.The microstructure and phase composition of the cladding layer with different carbon contents were observed and analyzed.According to the results of XRD and EDS tests,the reasons for the formation of the phase were explained from the perspective of kinetics and thermodynamics.In addition,the hardness,corrosion resistance,wear resistance and tensile strength of the cladding layer were tested.Combined with the composition of the phase and structure in the cladding layer,the above properties were analyzed mechanically.The results show that the cladding layer is mainly composed of ?(Fe,C),γ(Fe,Ni,Cr),and a small amount of fine carbides are dispersed in the austenite.It can be seen from the phase diagram simulation that a large amount of austenite appears in the initial stage of solidification,which is consistent with the XRD analysis results.According to the EDS spectrum analysis,the carbon content in the crystal is relatively high relative to the grain boundary,while the content of Cr and Mo is higher at the grain boundary,and the distribution of Ni is relatively uniform.The hardness of the cladding layer increases as the carbon content increases,and the hardness reaches the highest when the carbon content is 1.4 wt.%.Carbide increases the hardness of the cladding layer,but most of the C is solidified in the austenite matrix.The FeCrNiMoSiC cladding layer has good corrosion resistance in 3.5% NaCl,and Cr acts to form a passivation film to protect the surface of the cladding layer.As the carbon content increases,the corrosion resistance of the cladding layer decreases.After the sensitized cladding layer,intergranular corrosion occurs near the grain boundary,and the corrosion resistance of the cladding layer is further lowered.Abrasive wear,fatigue wear and adhesive wear of FeCrNiMoSiC cladding layer under sliding friction conditions.The carbide of the cladding layer acts as an anti-wear skeleton and enhances the wear resistance of the cladding layer.As the carbon content increases,the wear resistance of the cladding layer is further improved.In addition,as the carbon content increases,the tensile strength and crack sensitivity of the laser cladding layer increase.In this paper,the microstructure and properties of laser cladding layers with different carbon contents were studied,and the mechanism analysis was carried out.The research results have a certain guiding role for laser cladding to repair steel workpieces.