Study On Microstructure And Tribological And Wear Properties Of WC And TiC Reinforced Fe-based Composite Coatings

As an indispensable auxiliary device in the steel rolling process,the guide device can ensure the stability of the workpiece feed and ensure the output of the established high quality.Under the influence of irregular impact of feed steel,high rolling temperature and high-speed sliding environment,the surface of guide plate is prone to fatigue failure,wear failure and steel bonding failure.Therefore,it is very important to improve the hardness and wear resistance of the guide plate surface of the main components,and to prolong the service life of the guide device.In this paper,three kinds of hard phase Fe-based composite coatings with different contents were prepared on the substrate of GCr15 bearing steel by laser cladding technology,using LC3558 Iron-based alloy powder and hard phase WC and TiC as cladding alloy materials.By regulating the content of hard phase,the relationship between microstructure evolution and friction and wear properties of cladding layer was explored,and the Iron-based composite coating with high hardness and high wear resistance was obtained.(1)Iron-based composite coatings containing 20wt.%?30wt.%?40wt.%and50wt.%WC were prepared.The comparative study shows that there is a thin and narrow bonding zone at the interface between the substrate and the cladding layer,no obvious defect in the microstructure of the cladding layer.The reinforced phase of Iron-based composite coating with WC is mainly Fe₃W₃C and Fe₂W₂C,and a new hardening phase M₇C₃ is formed with the increase of WC content in the cladding layer.The hardened phase with high hardness Fe₃W₃C,Fe₂W₂C,M₇C₃ and WC particles dispersion distribution coating significantly improve the hardness of the cladding layer,in which the surface hardness of 50 wt.%WC iron-based composite coating reaches 1063.9HV_0.1,which is about 3 times that of the substrate.The hardness of 30wt.%WC cladding layer is the second,but wear resistance is the best and the weight loss is only9.1mg,which is less 40.1mg than total weight loss of the substrate.The wear machine is composed of abrasive wear and oxidation wear.According to the comprehensive analysis,the wear resistance of WC iron-based composite coating with 30wt.%is the best.(2)The temperature field and stress field of single-pass laser cladding Iron-based composite coating with 50%WC are simulated and analyzed by ANSYS Finite Element software.In the process of temperature field simulation,the maximum temperature along the scanning direction remains unchanged,then the temperature decreases gradually,which is in line with the expected heat transfer path.When the temperature changes with time at the equidistant nodes of the cladding layer,each node has a similar temperature change process,that is,it rises rapidly at first and then cools rapidly,and the maximum temperature of each node increases gradually in turn.In the process of stress field simulation,the stress in the bonding area between cladding layer and substrate is more concentrated,and the maximum residual tensile stress can reach 436MPa.At the same time,1mm accumulates at the joint of cladding layer and substrate at the distance from the surface of cladding layer,and the maximum residual tensile stress reaches 234 MPa,resulting in longitudinal cracks.(3)Prepared the Iron-based composite cladding layer with TiC(mass percentage)20%,30%,40%,and composite phase(TiC,WC)20%TiC+10%WC,10%TiC+20%WC.The metallurgical combination of the base material and cladding layer is better.The cladding layer with TiC hard phase is mainly composed of?-Fe,Fe₃C,TiC,(Cr,Fe)₇C₃ and Fe-Cr.The diffraction peak intensity of TiC cladding layer is higher at 40wt.%.The cladding layer of(TiC,WC)composite phase XRD is mainly composed of?-Fe,WC,TiC/(Ti,W)C_1-X,(Cr,Fe)₇C₃ and Fe WB.With the increase of the content of WC in the coating,the intensity of the diffraction peak also increases.In the mechanical properties of the cladding layer with only TiC and composite phase(TiC,WC),the hardness increases at first and then decreases.The cladding layer with40wt.%TiC content has the highest average hardness of 857.3 HV_0.1,which is 2.8 times that of the substrate.The addition of composite phase(TiC,WC)has no obvious strengthening effect on the hardness of the coating than that of hard phase TiC.However,in the analysis of wear resistance,the cladding layer with composite phase(TiC,WC)can bring more significant wear resistance.When TiC accounts for 10%,the weight loss is only 4.5mg,which is 1.6 times of the minimum wear of 30 wt.%TiC cladding layer(7.3mg).There are mainly abrasive wear,adhesive wear and surface oxidation wear in the wear mechanism.Based on the above analysis,the Iron-based composite coating with 30wt.%TiC and 10wt.%TiC+20wt.%WC has the best mechanical properties and can effectively improve the hardness and wear resistance of the Iron-based composite coating.Figure[84]table[11]reference[75]...