Study On Laser Cladding Corrosion Resistant Coating Of High Chromium Stainless Steel

The hydraulic support of coal mine plays an important role in supporting and protecting the"three-machine supporting"fully mechanized mining process.The column is the main load-bearing component of the hydraulic support.It works under the harsh environment for a long time.In the process of work,there are often spatters of rock refuse and cinders,and the surface of the column is scratched and worn.And it contains more corrosive substances and is easy to form electrochemical corrosion on the surface of the column,and the column is broken.In the event of an accident occurs,not only will it cause casualties,but it will take time and effort to replace the equipment and waste resources.It is of great significance to use the laser cladding technology to repair and remanufacture the surface of the hydraulic support column to improve the corrosion resistance of the column surface.In this paper,27SiMn steel is used as the base material for the hydraulic support column.The cladding material is X431-M2 iron-based alloy powder material.The corrosion-resistant coating is prepared on the surface of the base metal by semiconductor laser.The effects of laser cladding process parameters on the dilution ratio,microstructure and corrosion resistance of the cladding layer were studied.The reasons for the improvement of the corrosion resistance of the cladding layer were analyzed.The good combination with the matrix metallurgy and the crack-free pore defects and resistance were obtained.A cladding layer with excellent etching properties and applied to production.The results show that,while ensuring the uniform thickness of the cladding layer,the simultaneous change of cladding speed and powder feeding speed have little effect on the dilution ratio,microstructure and hardness of the cladding layer.The inner layer of the cladding layer contains plane crystals,columnar crystals,dendrites and equiaxed crystals.The composition phase is martensite and ferrite and a small amount of carbides and retained austenite.The segregation degree of alloy elements in the cladding layer is greatly affected by the process parameters,and the corrosion resistance of the cladding layer with larger segregation degree is poor.When the cladding speed is 380mm/min and the powder feeding speed is 58.5?60.5g/min,the dilution ratio of the cladding layer is the smaller,which is 9.886%,the internal structure of cladding layer is fine and compact,the degree of segregation is the smaller,the hardness is the higher,which is 57.3HRC,and the self-corrosion current density is the smaller,which is 0.5561 ×10-7A/cm2.The corrosion potential and pitting potential are the higher,which is-0.1348V and 0.2441V,and the corrosion resistance is the best.After the process optimization,the macroscopic morphology of the cladding layer is improved,the number of pores is reduced;the microstructure of the cladding layer is fine and compact,the degree of elemental segregation is reduced,the self-corrosion current density is 0.5561 x 10-7A/cm2,and the corrosion resistance is greatly improved;Good salt corrosion resistance was observed in the salt spray test.The optimization of the laser cladding process parameters improves the corrosion resistance of the surface of the hydraulic support column,improves the qualified rate of repaired products.