Study On The Bonding Performance Of Laser Discrete Pretreatment Substrate And Nickel Plating Layer Under Tensile Load

Electroplated super-abrasive grinding wheels not only have high hardness and high wear resistance,but also can adapt to a variety of complex curved surface processing.It is an extremely important abrasive tool.In the processing of electroplated super-abrasive grinding wheels,the combination of the metal hub substrate and the electroplated layer has a significant influence on the service life of the grinding wheel and the grinding performance of the grinding wheel.Therefore,how to improve the bonding performance of the metal hub substrate and the electroplated layer to prevent the abrasive from falling off prematurely and cause the grinding wheel to fail has always been a research focus in the field of grinding.Aiming at this problem,this paper proposes a new process method,namely,laser discrete pretreatment substrate re-plating,and through the hardness experiment,tensile experiment,and finite element simulation to study the effect of the new process on the bonding performance between the substrate and the coating interface.The main research contents are as follows:(1)The effects of the laser discrete quenching process on the micro-hardness distribution state of the sample matrix,the combined morphology of the substrate/coating interface and the microstructure morphology were studied.The results show that the laser discrete quenching process changes the microstructure of the 45 steel matrix,and generates a fine martensite structure with relatively strong corrosion resistance,high hardness,and low toughness in the laser quenching zone.The original matrix zone It is mesh ferrite and pearlite,and a "hard and hard" periodic hardness gradient is formed on the surface of the substrate;at the interface between the substrate and the nickel-plated layer,the boundary between the laser quenching zone and the nickel layer is a line A smooth straight line,and the junction of the original substrate and the nickel layer is an uneven curve.(2)Tensile comparison experiments of two groups of different samples were carried out to explore the effect of the laser discrete quenching process on the anti-stripping properties of the coating,the bonding properties of the substrate and the coating,and the overall tensile properties and load-bearing capacity of the samples.The results show that under tensile load,the coating of the laser discrete pretreatment sample still adheres to the substrate and never divestiture from the substrate.At the same time,the anti-stripping resistance of the coating is also much better than that of the untreated sample.After tensile fracture,the tensile strength of the treated samples increased from 750 MPa to 795 MPa;this also shows that the laser discrete pretreatment matrix can effectively improve the overall tensile strength and load capacity of the matrix/plating system.(3)Based on the finite element analysis of the tensile load of the sample,the effect of the laser quenching process on the interface stress and bonding properties of the 45 steel substrate and the nickel-coating was further explored.The analysis results show that the maximum interface normal force of the laser pretreated sample is lower than that of the untreated sample,and the overall interface shear force of the laser pretreated sample is significantly lower than that of the untreated sample;this means that the laser The nickel-plated layer of the pretreated sample is less prone to peeling of the coating,and the strain mismatch generated when the sample is pulled is also reduced,thereby effectively improving the bearing capacity of the substrate/plating interface and enhancing the substrate and the coating Of bonding strength.