Effect of Deep Cryogenic Treatment on Machinability and Corrosion Resistance of Titanium Grade 2 Alloy Using Electrical Discharge Machining Process

The present study explains the effect of Deep Cryogenic Treatment (DCT) of Titanium grade-2 alloy on machining using Electrical Discharge Machining (EDM) process. Machinability was assessed by considering three output process parameters: Material Removal Rate (MRR), Electrode Wear Rate (EWR), and Surface Roughness (Ra) developed over the machined surface. For the experimental investigations three input process parameters were used: peak current, Duty factor (τ), and Pulse on Time (TON). When compared to Non-Cryogenic Treatment (NCT), the DCT sample showed superior machinability, with the time required for machining reduced by an average of 20%. After DCT, the samples showed the highest material removal rate (0.496 mg/min), the lowest electrode wear rate (0.003 mm³/min), and the lowest surface roughness (3.375 μm). Gray Relational Analysis (GRA) was used for multi-objective optimization to determine the optimal value of input process parameters. The corrosion study was performed to investigate the impact of DCT on Titanium grade-2 alloy. The Potentiodynamic Polarization (PDP) study showed improved corrosion resistance on DCT, with I_Corr values decreasing from 2.7176 × 10⁻¹⁰ to 9.03998 × 10⁻¹¹ A. The corrosion rate of DCT sample was reduced from 0.18867 to 0.03138 μm/year resulting in an enhanced protection efficiency of 83.4%. The enhancement in corrosion resistance was due to the strengthening of passive oxide layers of Titanium grade-2 alloy after DCT, observed in the EIS study with the highest phase angle.