| At present,the corrosion and wear resistant coatings on the surface of parts in China are mainly prepared by electroplating chromium,thermal spraying or surfacing welding.In the coating prepared by thermal spraying,the porosity is high(porosity1%-2%)and the bonding strength is low.In the process of electroplating,there are serious pollution and harm to the environment.As a subversive coating technology,ultra-high speed cladding can not only greatly improve the deposition scanning rate,but also effectively avoid the traditional cladding lap temper problem,so that the coating has better corrosion resistance.Ultra-high speed laser cladding technology belongs to the advanced additive manufacturing and green manufacturing fields,and is one of the major strategic development directions of "made in China 2025".This paper with the method of synchronous send powder,developed by the use of ultra high speed laser cladding technology,preparation of scanning speed on the 45 steel substrate respectively 40 m/min,70 m/min,and 0.4 m/min of Fe base coating,and traditional laser cladding and ultra high speed coating prepared by laser cladding organization characteristics and performance comparison,at the same time,using the ultra high speed cladding technique was used to prepare the line scanning speed to 40 m / 70 m/min min,Ni base coating.By means of optical electron microscopy(OM),scanning electron microscope(SEM),X-ray diffraction(XRD),electrochemical workstation and microhardness tester,the structure,morphology,composition and corrosion resistance of the samples were analyzed.ANSYS WORKBENCH simulation software was used to select the appropriate heat source model and boundary conditions to establish the temperature field change model in the laser cladding process,and to investigate the temperature distribution in the ultra-high speed laser cladding and the conventional laser cladding process.The results show that:The Fe base coating thicknesses prepared in the ultra-high speed cladding state and the conventional cladding state were 100?m(40m/min),70?m(70m/min)and460?m(0.4m/min),respectively.The width of the heat-affected zone is 40?m(40m/min),40?m(70m/min),and 1180?m(0.4m/min).The coating grain is finer under the condition of ultra-high speed cladding.The microhardness of the coating(70m/min)is 180hv0.2 higher than that of the conventional cladding coating,and350hv0.2 higher than that of the substrate 45 steel.The corrosion potential Ecorr of the coating prepared at the scanning speed of 70m/min was 0.571 V higher than that of45 steel.With the increase of the scanning speed,the corrosion current density of the prepared coating gradually decreased,and the corrosion current density of the prepared coating was 2.463(?A·cm-2)lower than that of 45 steel at the speed of70m/min.The thickness of Inconel 625 coating in ultra-high speed laser cladding state is respectively 150?m(40m/min)and 80?m(70m/min),and the thickness of heat affected area is about 70?m(40mmin)and 65?m(70m/min).The hardness distribution of the coating is relatively uniform.The hardness of the coating prepared under the online scanning speed of 70m/min can reach 300hv0.2.The corrosion potential of the coating with a speed of 70m/min was 0.44 v higher than that of 45 steel.The corrosion current density Icorr decreased by 0.36(?A·cm-2)compared with45 steel at A speed of 70m/min.The coatings prepared in ultra-high speed cladding state have good corrosion resistance and finer grain structure.At the same time,the range of the heat-affected zone is significantly reduced,which is similar to the simulation results of the temperature field.It is found that solute interception occurs during ultra-high speed cladding,which is the main reason for the low dilution rate and good performance of the coating. |
PDF Full Text Request