Research On Laser Surface Modification Of Stainless Steel Valve Material

Stainless steel valves are key components in the oil and gas storage and transportation pipeline transportation system.Under their service conditions,they are susceptible to the erosion and erosion of the internal transportation medium and the rust,extrusion,vibration,and deformation of the external soil atmosphere.Destruction and other situations.In order to improve the service life of stainless steel valve materials,this project combines its service environment and uses lasers to prepare strengthened coatings on the surface of stainless steel valve materials,and explores its temperature field distribution,structure,comprehensive performance,and strengthening mechanisms to achieve surface coating.The optimization and comprehensive coordinated control of layer structure and performance,so as to improve the durability and reliability of oil and gas pipeline facilities,are of great significance to the research on the preparation and repair of the surface of stainless steel materials by laser intensification technology.The main research work and conclusions are as follows:(1)The ANSYS software was used to simulate the three-dimensional transient temperature field of stainless steel valve materials,to explore the law and mechanism of the effect of different process parameters on the material surface strengthening coating,and the orthogonal experimental design was used to analyze the influence and weight of the temperature field distribution.The results show that,affected by the energy input,the action time per unit area and the degree of energy dispersion,higher laser power,lower scanning speed and smaller spot diameter will increase the temperature value of the temperature field of the strengthened coating,and the melting width will be The penetration depth increases,the temperature span increases,the density of isotherms increases,and the temperature gradient becomes more complicated.The coating penetration and temperature gradient are most affected by the laser power,and the penetration width and peak temperature are most affected by the laser scanning speed.Combining with the service conditions of stainless steel valve materials,according to the weighted results of orthogonal experiments and simulations,a combination of process parameters that is more reasonable for actual production is selected to provide data support for subsequent experiments and actual projects.(2)Based on the selection of process parameters that are more reasonable for actual production by simulation,the LDF 4000-40 high-power semiconductor laser is used to prepare a strengthened coating on the surface of the stainless steel valve material,and the laser surface enhancement performance is studied to explore its macroscopic appearance,Strengthening effect and mechanism of microstructure,microhardness,electrochemical corrosion and friction and wear.The results show that the width of the enhanced surface along the scanning path increases,and the cross-section is arcuate.Affected by the cooling crystallization conditions,the surface layer of the strengthening zone is equiaxed crystals,the middle part is columnar crystals and equiaxed crystals,and the bottom part is flat crystals.Affected by the high temperature action of the laser,the elements such as C,Fe,and Cr in the strengthened zone diffuse.Affected by the effects of fine-grain strengthening,the hardness of the strengthened zone is increased to 1.5 times that of the substrate,the corrosion current density is increased to 1.6 times that of the substrate,the potential is positively shifted by547 m V,the abrasion loss in the strengthened zone is reduced to 0.37 times that of the substrate,and the friction coefficient is reduced to that of the substrate.0.83 times of that.The tendency of corrosion reaction is reduced,the corrosion rate is increased,and the wear resistance is enhanced.The wear mechanism is mainly abrasive wear.(3)In order to further improve the strength and hardness of the stainless steel valve material on the basis of the research on the laser surface enhancement performance,the RFL-C1000 laser was used to prepare the WC content on the surface of the stainless steel valve material to be 0 wt.%,7.5 wt.%,10 wt.%,and 20 wt.%,respectively.wt.%,40 wt.%,60 wt.% composite coatings,the laser surface WC-enhanced Ni-based composite coatings were studied,and the effects of WC content on the porosity,crack sensitivity,phase structure,and elements of composite coatings were explored The mechanism and evolution law of composition,structure morphology,microhardness,corrosion resistance and wear resistance at various temperatures.The results show that the coating is mainly composed of planar crystals and dendrites,and the internal WC unmelted particles are unevenly distributed and there is a "agglomerate" effect.With the change of WC content,the porosity is affected by the gas escape rate and the cooling rate of the molten pool,and the number and distribution of cracks are affected by the thermal stress and phase transformation stress.Affected by solid solution strengthening and dispersion strengthening,the average microhardness of the WC-60 coating is the highest,which is about 1.67 times that of the WC-0 coating.Affected by the refinement of the structure,electrochemical uniformity and the number of WC particles acting as the primary battery,the WC-10 coating has the least driving force for the corrosion reaction and the WC-20 coating has the strongest corrosion resistance.Affected by the strengthening phase distribution and solid solution strengthening,the wear resistance of the WC-20 coating is the highest,which is about 1.55 times that of the WC-0 coating.The wear mechanism of WC-0 coating is plastic deformation,the wear mechanism of WC-5,WC-7.5,WC-10,WC-20 coating is adhesive wear and plastic deformation,and the wear mechanism of WC-40 and WC-60 coating is wear.Grain wear.Affected by oxidation rate and toughness,WC-5,WC-7.5,and WC-10 coatings have the highest friction coefficient and maximum wear at 600°C.Under the abrasion condition of 20℃,the coating will produce fatigue wear and slight adhesive wear.Under the abrasion condition of 300℃,the coating will produce adhesive wear and plastic deformation.Under the abrasion condition of 600℃,the coating will produce abrasive wear and adhesive wear.