Research On M2 Coating Prepared By Ultra-High Speed Laser Cladding

Laser cladding technology is a laser surface processing technology that uses high-energy laser beams to prepare surface coatings.According to the selection of cladding materials,the required surface properties can be obtained.It is suitable for surface modification and repair and reuse of damaged parts.It is widely used in metallurgy,chemical industry,shipbuilding,aerospace and other fields.However,traditional laser cladding has problems such as low cladding efficiency and high heat input to the substrate.The ultra-high-speed laser cladding technology realizes the preparation of high surface flatness and high-quality cladding layers with high cladding efficiency through the control of the cladding powder,which has great research value and market competitiveness.Due to poor working conditions,rolls are common shaft parts that are scrapped due to surface failure,resulting in waste of resources and environmental pressure.9Cr2Mo is a more commonly used steel for rolls.M2 high alloy steel has good hardness,wear resistance and red hardness.It is a commonly used tool,die,roll and other component materials.Better mechanical properties can be obtained by improving the processing technology.The ultra-high-speed laser cladding is used to prepare the M2 cladding layer on the surface of 9Cr2Mo steel,and the selection of process parameters has a decisive effect on the morphology,size,structure and properties of the cladding layer.Through finite element simulation and physical experiment research,the cladding layer morphology,size,structure,and mechanical properties are studied,and the influence of process parameters on the forming performance and mechanical properties of the cladding layer is summarized.Based on the ultra-high-speed laser cladding process and forming characteristics,ABAQUS finite element simulation software is used to establish a finite element model to obtain the temperature field changes.The simulation results show that the upper part of the cladding layer has a higher temperature,a smaller temperature gradient,and a larger temperature gradient at the bottom of the cladding layer.The heat input at the contact position between the edge of the cladding layer and the bottom is low,and the heat loss is too large to achieve an ideal cladding bonding shape.Appearance,the substrate near the cladding layer has different degrees of temperature rise and cooling processes,which will have an impact on the structure of the substrate.Studies have shown that as the cladding speed increases,the size of the cladding layer decreases and the aspect ratio increases,which has the greatest impact on the shape and size of a single cladding pass.Increasing the distance between the cladding channels,reducing the laser power and increasing the cladding speed will reduce the energy density per unit area input to the cladding layer and obtain a better surface morphology of the multi-pass cladding layer.The microstructure of the cladding layer under different process parameters was studied,and it was found that the cladding layer is dominated by fine equiaxed crystals,with fine network carbides distributed between the crystals,and there are some retained austenite and a small amount of M₂C at room temperature.By increasing the laser power,reducing the cladding speed,and reducing the cladding channel spacing,a higher input energy density can be obtained,and the tissue size will also increase.The laser power has the most obvious effect on the tissue size,and the cladding layer The average microhardness will also increase,and the hardness distribution will be more uniform and the range of change will be smaller.The M2 cladding layer prepared by ultra-high-speed laser cladding not only has a higher hardness than the substrate,but also greatly improves the wear resistance.