ELECTRICALLY-ASSISTED MACHINING OF TITANIUM ALLOY TI-6AL-4V AND NICKEL-BASED ALLOY IN-738: AN INVESTIGATION

Despite their increasing use in leading industries, manufacture of alloys with superior mechanical properties have been a big challenge in the recent years. Researchers have been working on using assisted or augmented processes to overcome this challenge, with methods such as ultrasonically assisted, thermally assisted, vibration-assisted, magnetic field-assisted, and laser-assisted machining. Utilizing electrical assistance in manufacturing has not caught much attention due to its difficult-to-apply nature. However, it is possible to increase the ductility and machinability (through reduced flow stress) of certain metallic materials through the use of electricity. In this method, the electrical current resistively heats the material while aiding in deforming the material through the electroplastic effect. The limited amount of work in this topic is mainly focused on exploring the forming characteristics of relatively softer materials. Application of this augmentation to alloys with superior mechanical properties at elevated temperatures, on the other hand, has not been explored. This study aims to fill in that void through an investigation of applying different currents through the tool concentrated on the tool-workpiece contact zone. Both the titanium alloy Ti-6Al-4V and the nickel-based superalloy IN-738 were investigated, and the results showed that for both materials, there are two separate thresholds that need to be considered in any analysis. The first threshold is where the material starts to get deformed, below which no significant divergence from the baseline (no current) tests was observed. After exceeding this value, machining forces start decreasing with increasing current up to a certain point (second threshold) where the effect of electric current is reversed. If the second threshold is surpassed, the machining forces increase rapidly. Findings of this study can be used in assisting the machining of such materials.