Research On The Electrolytic-Magnetic Abrasive Finishing Of Nickel-based Superalloy GH4169

Because of antioxidation, high temperature strength, corrosion and fatigue resistance, and other outstanding advantages, nickel-based superalloy material has been widely used in the manufacture of key components in aviation, aerospace, shipbuilding, power, transportation and other important sectors, such as blisk, turbine disk, turbine shaft, seal ring, etc., the surface quality of these components directly affect operational performance and service life of the entire mechanical system, so it is necessary to improve the surface quality of these parts. However, nickel-based superalloy material has become a typical difficult-to-machine material because of its good physical and mechanical properties, which brings great difficulty to the precision machining. Investigation and research on the precision machining of nickel-based superalloy GH4169 were carried out, the results shows that traditional precision machining methods can improve the surface quality of the workpiece in a certain extent, but for complex structural components such as blisk which has narrow working space,thin blade and large surface distortion, it is easy to produce extra vibration to reduce the stability of cutting process, and then causing the cutting shape deformation and other serious consequences. As a nontraditional method of precision machining processes, magnetic abrasive finishing(MAF) has many attractive advantages such as good flexibility, self-sharpening of magnetic abrasive particles(MAPs), as well as easy controllability. So it can make up for the shortcomings of traditional processing methods, but when the machinability of workpiece is poor, the processing efficiency of magnetic abrasive finishing is relatively low,which can not meet the needs of industrial production. Therefore, it is necessary and urgent to find a new technology combining with magnetic abrasive finishing to form a composite finishing method, which can improve the precision machining efficiency of nickel based superalloy GH4169.Electrolytic polishing process(EPP) is based on the principle of electrochemical anodic dissolution, The EPP process is not affected by the hardness of workpiece itself and suitable for most of metallic materials, and its efficiency is high as well in theory. Therefore, based on the mechanism of magnetic abrasive finishing, electrolytic-magnetic abrasive finishing(EMAF) combining the magnetic abrasive finishing process and electrolytic polishing process reasonably and effectively was used to polish nickel-based superalloy GH4169 plane in this article. Based on the basic theory of magnetic abrasive finishing and electrolytic polishing process, the basic principle of the electrolytic-magnetic abrasive finishing is further explored and discussed and then composite grinding device with the characteristics of separation form of electrode-magnetic pole was designed, so this device can effectively avoid the short circuit problem in machining process, and the electrolytic polishing process and magnetic abrasive finishing are independent and interrelated, the factors affecting the effects of each process can be controlled simply and effectively; In the process of electrolytic-magnetic abrasive finishing, the matching problem of electric field intensity and magnetic field intensity exists and there are many factors that affect the final processing results, so the matching problem and the influence factors was discussed and analyzed; In order to explain the formation process of the passive film, the electrochemical characteristics of nickel-based superalloy GH4169 were verified by theoretical and experimental verification. the results show that the introduction of electrolytic polishing process was helpful to the surface modification of the workpiece material, the machining efficiency and grinding quality of nickel-based superalloy GH4169 can be effectively improved with the method of electrolytic-magnetic abrasive finishing by comparing the processing results; The grinding performance of magnetic abrasive particles(MAPs) is the key factor affecting the processing quality of magnetic abrasive finishing, serious failure of magnetic abrasive particles will occur in the process of polishing nickel-based superalloy and other hard materials by single magnetic abrasive finishing(MAF),the stress analysis and failure analysis of the magnetic abrasive particles are carried out, nickel-based superalloy GH4169 was polished by electrolytic-magnetic abrasive finishing for 10 min and then the magnetic abrasive particles remaining on the magnetic poles were collected as the test target for experiments and experimental results show that electrolytic-magnetic abrasive finishing can effectively prolong magnetic abrasive particles’ service life.