MIG与CMT熔覆工艺对Cu基涂层与母材组织性能的影响OA

Arc cladding corrosion-resistant coatings are one of the primary methods to enhance the surface performance of workpieces and extend their service life.To thoroughly investigate the effects of arc cladding process methods on the microstructures and mechanical properties of coatings and base metals,optimize the cladding process with good coating quality and minimal impact on base metal properties,and ensure product service safety,MIG and CMT cladding technologies were respectively used to clad copper alloy coatings on the inner surface of hydraulic cylinders.A comparative study was conducted on the effect laws of the two process methods on coating forming quality,coating microstructure morphology,coating corrosion resistance,base metal interface morphology characteristics,base metal heat-affected zone(HAZ)morphology,base metal microstructure morphology,as well as base metal yield strength,low-temperature impact toughness,and microhardness.Both MIG and CMT cladding coatings had dense structures and good bonding,with no obvious defects such as pores and cracks.Both cladding coatings were mainly composed of α-phase,β-phase,and κ-phase.However,the MIG cladding coating contained a large number of spherical and blocky base metal structures.The interface between the MIG cladding coating and the base metal was uneven.During the cladding process,part of the base metal melted and was involved in the molten pool,and existed in the coating as spherical and columnar structures after solidification,forming base metal"inclusions".This not only increased the coating dilution rate but also affected the mechanical properties of the coating.The CMT cladding coating had uniform element distribution and low coating dilution rate,and the interface between the cladding coating and the base metal was serrated.Its steady-state open-circuit potential was ‒0.44 V,self-corrosion potential was ‒0.67 V,and corrosion current density was 4.46 μA/cm2,which were better than those of the MIG cladding sample(0.47 V,‒0.72 V and 4.81 μA/cm2).Therefore,the CMT cladding sample had better corrosion resistance. Both MIG and CMT cladding processes have a certain degree of effect on the microstructure and properties of the base metal.The HAZ width of the CMT cladding sample is 890 μm,which is lower than that of the MIG sample(1 025 μm).The microstructure of the HAZ in both CMT and MIG samples is primarily composed of coarse ferrite and cementite.Notably,a small amount of Widmannstatten structure is observed in the HAZ of the MIG sample.Compared with the cladding samples,in addition to the obvious change in the HAZ microstructure of both CMT and MIG samples,the microstructure in the near-HAZ of the base metal has undergone an obvious coarsening phenomenon.The microhardness,yield strength,and low-temperature impact toughness of the base metal in the near-HAZ of the CMT cladding sample are 257HV,707 MPa,and 135 J respectively.Compared with the uncladded base metal,these values decrease by approximately 10.5%,7.0%,and 17.7%respectively.For the MIG sample,the corresponding values are 249HV,701 MPa,and 125 J,with decreases of 13.5%,7.7%,and 23.3%compared with those of the uncladded base metal.The degree of decrease is higher than that of the CMT process.Compared with MIG,the CMT cladding process has lesser impact on the microstructure and properties of the base metal.