Experimental research on the counter-rotating electrochemical machining of 304 stainless steel and Inconel 718 alloy

摘要

In Electrochemical machining (ECM), anodic dissolution process is strongly affected by theelectrochemical behavior of the target metal. This study aims to improve the counter-rotatingelectrochemical machining (CRECM) performance of lug boss on Inconel 718 on basis of differentdissolution behaviors of metals. The dissolved surfaces of 304 stainless steel and Inconel 718 at variouscurrent densities were examined using scanning electron microscope, energy-dispersive X-rayspectroscopy, and electrochemical impedance spectroscopy. The profiles and surface qualities of themachined lug bosses were compared. The results indicated that the 304 stainless steel workpiecepresented substantially better machining performance than Inconel 718 due to its favorable localizationeffect. Straight lug bosses with small fillet radii were fabricated in 304 stainless steel. In contrast, thesidewall of a lug boss formed on the surface of Inconel 718 workpiece was tapered and had a large filletradius because of substantial corrosion on its top surface. On this basis, a 304 stainless steel coating layerwas employed to improve CRECM performance during machining of a high lug boss on Inconel 718.The experimental results showed that the employment of 304 stainless steel coating layer could preventthe surface of lug boss on Inconel 718 from dissolution and therefore improve the machining accuracyeffectively.