| The remanufacturing industry is a green remanufacturing industry of emerging national strategic.It aims to restore the performance of equipment and its parts and components,reduce energy consumption in the manufacturing industry,and effectively reduce pollution to the environment.This will enable the manufacturing industry to upgrade in the green and environmental direction while creating huge economic benefits for the country.With the rise of the remanufacturing industry in recent years,pulsed cold welding repair technology has also developed rapidly.Pulse cold welding repair technology is a pulse signal based surface repair technology that can repair defects of parts.In the actual application of this technology,how to make the substrate and the repair layer have a good combination of force,to obtain a better repair effect,is the technology currently facing the problem.This subject revolves around these problems that need to be solved,using pulsed cold welding technology to remanufacture and repair 45 steel,which is a commonly used metal material,and systematically studies its repair mechanism.Firstly,the large-scale finite element numerical analysis software ANSYS was used to simulate the temperature field of the pulse cold welding repair process using the life-and-death element technology.At the same time,the temperature value was measured experimentally,and the current and repair speed were used to analyze the influence of temperature field distribution during the repair process.Then,a 50mm x 6mm x 1mm regular body notch was machined at the symmetry center of a 45mm×50mm×10mm 45 steel base body.Pulsed cold welding repair technology was used to remanufacture the gap and prepare a Q345 repair layer.Using metallographic microscope,scanning electron microscope?SEM?,energy dispersive spectroscopy?EDS?,X-ray diffraction,and microhardness tester,the phase structure,microstructure,element diffusion,and hardness distribution of the bonding region between the substrate and the repair layer were investigated.Finally,the selection of the optimal process parameters for the pulsed cold welding process was discussed through the repair of the quality of the layer.The results show that the temperature field of pulse cold welding repair process can be successfully simulated by using the life-and-death element technology;in order to improve the repair effect,the current value should be properly increased and the repair speed should not be too slow.A fusion zone is between the matrix and the filler material,and the repair quality is good;the diffusion of the element is accompanied in the fusion zone,and??Ni,Cr,Fe?,Co3Fe7,and C0.055Fe1.945.945 are detected at the repair interface.The presence of new phases indicates that the matrix and repair layer are metallurgically combined during the pulse cold welding repair;when using the pulse cold welding technique,the selection principle of the repair frequency should satisfy that all the parts on the repaired area are fused properly,and the principle of selection of the energy amplitude should satisfy the organization that the overheated tissue will not appear after being repaired;the HAZ range after the repair is very small.The weld repair layer has a lower hardness than the base body,which facilitates the mechanical treatment of the later parts.In the experimental range,the optimal frequency of pulse cold welding is 25HZ,and the energy output amplitude is 40%.Through the study of pulse cold welding temperature field.The systematic analysis of the phase structure,microstructure,element diffusion and hardness distribution of the cross-sections after repair under different process parameters was conducted in order to provide theoretical support for the improvement of the quality of remanufactured products by pulsed cold welding repair technology. |
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