Surface integrity of Inconel 718 in electrical discharge grinding

Electrical discharge grinding has large potential application prospect in Inconel 718 machining. Surface integrity of Inconel 718 in electrical discharge grinding is characterized by a variety of methods in the paper. The ground surface morphology is observed by scanning electron microscope. Electrical discharge grinding zone and pure grinding zone are generated on the ground surface in electrical discharge grinding. Electrical discharge grinding zone increases with the increases of depth of cut, feed speed, voltage, current, and the ratio of pulse width to pulse interval. Subsurface grain deformation is detected by means of electron backscatter diffraction method. In electrical discharge grinding zone, local misorientations are much less than those in pure grinding zone. Moreover, they tend to distribute along the grain boundaries in pure grinding zone. Moreover, there is almost no recrystallization in both types of zones. Electrolytic corrosion method is adopted to investigate the corrosion resistance. It is found that the corrosion resistance of electrical discharge grinding zone is much poorer than that of pure grinding zone. Furthermore, nano-indentation experiment is executed to explore the nano-mechanical properties. The results show that the hardness and modulus of material from low to high are respectively electrical discharge grinding, bulk, and pure grinding. It also indicates that the recast layer could be removed more easily during subsequent precision machining.