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Study On SLM Forming Of Inconel 625 Alloy And Subsequent Surface Magnetic Abrasive Finishing Process

Posted on:2024-08-19Degree:MasterType:Thesis
Country:ChinaCandidate:N LiuFull Text:PDF
GTID:2531307136473934Subject:Mechanics (Professional Degree)
Abstract/Summary:PDF Full Text Request
There is urgent to seek an integrated method of design and manufacture,because of the higher requirements for the lightweight,integration,compounding and complexity modern aerospace equipment.Selective laser melting(SLM)near-net forming complex nickel-based superalloy components is an effective solution to solve the above problems.However,the characteristics of layer-by-layer stacking based on SLM lead to uneven tissue properties and poor surface quality of the formed parts,making it difficult to meet the requirements of highend equipment for service performance and surface functionality.Therefore,SLM process optimization and subsequent surface treatment are stringent issues to be addressed.In this paper,Inconel 625 nickel-based high-temperature alloy for aerospace applications was selected for multi-group process optimization experiments,followed by standard heat treatment of the formed parts;CBN/iron-based spherical composite magnetic abrasives prepared by atomized fast-setting methodology were used for the experimental study of magnetic grinding on the surface of SLM Inconel 625.The main work and results are as follows:(1)Inconel 625 SLM process parameters optimization and prototype forming.Through27 sets of SLM forming Inconel 625 densification tests,the causes of irregular pore formation under different laser energy densities were uncovered.The optimal combination of process parameters was determined as laser power 200 W,scanning speed 800 mm/s,and scanning spacing 120 μm,and the highest densification of Inconel 625 could reach 99.702%.After determining the optimal forming parameters,SLM forming 90° plate samples were subjected to solid solution and double-stage aging heat treatment.The anisotropy of the microstructure of the deposited samples was significantly improved after the heat treatment.(2)Basic research on magnetic abrasive magnetic grinding of SLM Inconel 625 sample parts.The CNC milling machine based on spindle modification was constructed as a grinding platform.The simulation of the static magnetic field of the slotted N52 Nd Fe B permanent magnet pole was carried out to determine the required strong induction strength and the appropriate abrasive filling when the processing gap was taken as 2~3 mm.The force of magnetic abrasives in different states and the generation of grinding pressure were analyzed.The advantages of its grinding performance were summarized by analyzing the principle of preparing spherical composite magnetic abrasives by gas atomization and rapid solidification methodology.(3)Optimization of the side surface process of magnetic grinding SLM Inconel 625 sample parts was carried out.Based on the response surface methodology for magnetic grinding process optimization experiments,the optimal grinding parameters were determined as spindle speed 1200 r/min,feed rate 14 mm/min and machining gap 2.2 mm.The surface roughness of the final magnetic grinding sample was reduced from 602 nm to Ra 43 nm,showing a surface texture with good uniformity and flatness.(4)The surface quality of MAF samples was evaluated and the material removal mechanism was explored.The changes in surface integrity before and after grinding were analyzed and compared from multiple perspectives of surface roughness,material removal,three-dimensional morphology,microhardness,residual stress,and hydrophobicity.It was shown that the material removal mechanism of magnetic grinding SLM Incoenl 625 nickelbased high temperature alloy was a combination of plastic removal by micro cutting edge and shearing and squeezing by magnetic abrasives on the sample surface,and the CBN/Febased magnetic abrasive did not change the surface chemistry.The surface morphology after finishing was accumulated by numerous disordered plastic micro-scratches.The research work can provide some theoretical support and technical support for the SLM forming process and subsequent surface finishing of Inconel 625 nickel-based hightemperature alloy.
Keywords/Search Tags:Selective laser melting(SLM), Inconel 625 Ni-based superalloy, Magnetic abrasive finishing(MAF), Process optimization, Surface quality
PDF Full Text Request
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