Study On Microstructure And Properties Of Hydraulic Cylinder Remanufactured By Laser Cladding

Fully mechanized mining is the main way of coal mining in my country,and hydraulic support is an important fully mechanized mining equipment.As one of the important components of the hydraulic support column,the hydraulic cylinder provides a safe and stable working surface for the fully mechanized mining support.Working in a harsh production environment for a long time,the surface of the hydraulic cylinder is prone to wear failure and rust failure,which has a huge impact on the service life of the hydraulic support.There are a large number of failed and discarded hydraulic cylinders in my country every year.If the surface can be repaired by remanufacturing methods,the economic benefits can be maximized on the basis of environmental protection and energy saving.Therefore,this project relies on the National Natural Science Foundation of China,"The Service Life Prediction Method and Experimental Research of Additive Remanufactured Mechanical Parts(51505268)",and takes27 Si Mn steel and hydraulic cylinder parts,which are commonly used materials for hydraulic cylinders,as the objects,and the laser cladding process for them.The parameters are optimized,and the remanufactured structure and performance are studied.The details are as follows:First,in order to obtain the single-channel cladding layer with the best comprehensive performance,the research and optimization of the laser cladding remanufacturing process for the 27 Si Mn steel plate was carried out.A four-factor and three-level orthogonal test was designed,and the optimal process parameters for single-pass cladding were obtained by using the weighted comprehensive evaluation method: laser power 2400 W,powder feeding speed20g/min,scanning speed 15mm/s,defocus amount +2mm;and On this basis,the optimal overlap ratio is 50%.At the same time,the microstructure,hardness and wear properties of the cladding layer under the optimal combination of cladding process parameters are studied.The results show that the performance of the cladding layer under the optimal process parameters is better than that of the substrate,indicating that this parameter can be used as the entity of the hydraulic cylinder Process parameters for cladding remanufacturing.Secondly,in order to obtain a cladding layer with dense structure,high hardness and good bonding strength,the effects of laser power,scanning speed and defocus amount on the morphology,size,structure,microhardness and bonding strength of the cladding layer were studied.The test found that the cladding layer has no obvious defects such as pores,and the degree of bonding is good.By increasing the laser power and scanning speed,and reducing the defocus amount,the grains of the cladding layer can be refined and the gap between the cladding layer and the substrate can be improved.binding strength.Thirdly,in order to obtain multi-layer cladding layers with excellent wear resistance,the effect of process parameters on the remanufactured surface wear properties was studied.The friction coefficient,wear loss weight and wear section profile are obtained through experiments to characterize the wear performance.The analysis found that the wear mechanism of the specimen was mainly severe abrasive wear,accompanied by a small amount of adhesive wear,and there were many and deep furrows on the wear surface;the laser power and scanning speed could be increased to obtain higher wear resistance.Cladding layer.Finally,Fe-Cr-Ni cladding layers were prepared on the inner and outer curved surfaces of the waste hydraulic cylinder,and the microstructure,microhardness,bonding properties and wear properties of the inner and outer curved cladding layers were analyzed respectively.The comprehensive evaluation of the remanufactured and repaired hydraulic cylinder provides a reference for the application of laser cladding in the remanufactured repair of the actual hydraulic cylinder.