Investigation on pitting corrosion rate of Micro Plasma Arc Welded Titanium (Ti-6Al-4V) alloy sheets in KBr solution using TOPSIS

Titanium is having good anti-corrosion properties in both basic and acidic medium. However, when it is subjected to severer heating processing like welding, there is a possibility of corrosion formation at the weld joint. In the present work Pulsed current MPAW is used for joining 0.5 mm thick Titanium (Ti-6Al-4V) alloy sheets. Peak Current, Base Current, Pulse Rate and Pulse Width are considered as input parameters and fusion zone corrosion rate is considered as output response. Four factors and five levels are considered. Taguchi L 25 orthogonal matrix is adopted and 25 experiments are performed. Linear Polarization method is adopted and corrosion rates are measured from Tafel plots for three different mediums namely 0.5N KBr, 1.5N KBr, 1.5N KBr and 2N KBr. Empirical mathematical models are developed using statistical software (MINITAB). Analysis of Variance (ANOVA) is carried out at 95% confidence level. Effects of welding parameters on corrosion rate are studied. Multi objective optimization of corrosion rate for the three mediums was carried out using TOPSIS (Technique for Order Preference by Similarly to Ideal Solution).