Optimization of wire-fed electron beam repair deposition on Inconel-718: Taguchi analysis of heat-affected zone hardness and width

Inconel-718 components often require in-situ restoration of local cavities or cracks. The present study explores wire-fed electron-beam welding (EBW) as a low-heat-input repair technique and employs a Taguchi L9 orthogonal array to optimise voltage (28-32 kV), current (18-22 mA), welding speed (9-11 mm s-1) and wire-feed rate (25-35 mm s-1). Nine coupons (25.4 mm x 25.4 mm x 3.556 mm) with 9.271 mm blind holes were filled under high vacuum. Rockwell-B hardness and heat-affected zone (HAZ) width were the performance metrics. The optimum condition (30 kV/18 mA/10 mm s-1/25 mm s-1) yielded a peak HAZ hardness of 95 HRB, whereas the combination of 28 kV/20 mA/11 mm s-1/30 mm s-1 limited HAZ width to 0.30 mm. Wire-feed rate dominated hardness, while voltage controlled HAZ width. Although extensive research has been conducted on EBW, the use of wire-assisted EBW as a repair-filling method for Inconel-718 has been rarely explored. This study addresses this gap by (i) combining a precision wire feeder with an EB gun for cavity restoration and (ii) evaluating both the hardness and width of HAZ using a Taguchi optimization approach.