Study On Process,microstructure And Properties Of Laser Cladding Inconel 625

As oil and gas development continues to extend into deeper and ultra-deep formations,more and more acidic gas fields containing high concentrations of H₂S and CO₂ corrosion media are being developed.Many oil and gas extraction equipment,such as wellhead devices,are subject to corrosion and fracture due to the acidic environment,posing a threat to equipment integrity.Typically,corrosion-resistant alloys are welded onto the surface of wellhead devices,but the quality of the welded layers is poor,and a significant amount of the repair layer is scrapped,resulting in economic losses.Therefore,it is necessary to seek new manufacturing processes for wellhead devices.This paper adopts laser cladding technology to melt Inconel 625 onto the equipment substrate surface and studies the laser cladding process and its microstructure properties.The specific research content is as follows:Based on the central composite test design method,single-track laser cladding experiments were conducted to explore the influence of process parameters on single-track cladding width,height,and wetting angle,and the laser cladding process parameter window was determined.A neural network prediction model of the process parameters and single-track cladding width and height was established.Multiple-track laser cladding experiments were carried out using a single-factor method to explore the influence of process parameters on the surface ripple,effective height,and dilution ratio of the multiple-track cladding layer.The laser cladding thermal coupling model was established to investigate the effect of process parameters on the laser cladding temperature field and stress field.The influence of process parameters on the microstructure was studied by observing the microstructure changes in the cladding layer.The relationship between process parameters and the corrosion resistance of the cladding layer was explored through electrochemical corrosion tests,and the optimal process parameter combination for corrosion resistance performance was determined.The research results are as follows:（1）The appropriate process parameter window is 30 J/mm²≤EAD≤100 J/mm²,2600 J/g≤EMD≤6000 J/g,and the size of the cladding layer is significantly affected by the interaction of process parameters.The PSO-BP neural network model has a high fitting and prediction accuracy for the cladding layer size.The surface ripple of the single-layer multi-track cladding layer increases with the increase of the powder feeding rate and decreases with the increase of the scanning speed,with no significant corresponding relationship with the laser power of the cladding layer.The effective height increases with the increase of the powder feeding rate and laser power and decreases with the increase of the scanning speed.The dilution ratio decreases with the increase of the powder feeding rate and scanning speed and has no significant corresponding relationship with the laser power.（2）During the laser cladding process,the temperature at the center of the cladding decreases towards the periphery.With the increase of laser power,the highest temperature during the cladding process increases,the positive stress component in the X and Y directions increases,and there is no significant change in the positive stress component in the Z direction.With the increase of scanning speed,the highest temperature during the cladding process decreases,the positive stress component in the X and Y directions decreases,and there is no significant change in the positive stress component in the Z direction.（3）The microstructure of the cladding layer from the substrate to the surface of the cladding layer is successively composed of planar crystals,cellular crystals,columnar crystals,and equiaxed crystals.With an increase in powder feeding rate,the content of cellular crystals and columnar crystals in the cladding layer increases,while the quantity of equiaxed crystals decreases.With an increase in scanning speed,the content of cellular crystals and columnar crystals in the cladding layer decreases,while the quantity of equiaxed crystals increases.With an increase in laser power,the quantity of cellular crystals and columnar crystals increases,while the quantity of equiaxed crystals decreases.When the powder feeding rate is 0.33 g/s,the laser power is 1.2 k W,and the scanning speed is 9 mm/s,the formed cladding layer has excellent quality and strong resistance to pitting corrosion.The research results of this paper can provide reference and guidance for the engineering application of laser cladding.