Welded Ti-6Al-4V joints are employed in nuclear engineering, civil industries, military and space vehicles. Laser beam welding has been used for welding thanks to its advantages in terms of increase in penetration depth and reduction of possible defects; moreover a smaller grain size in the fused zone is benefited in comparison to either TIG and plasma arc welding, thus providing an increase in the tensile strength of the welded structures. The aim of this work is to develop and test the regression model for a number of crucial responses. The study has been carried out on 1 mm thick Ti-6Al-4V plates; a square butt welding configuration was considered employing a disk-laser source. A three level Box-Behnken experimental design is considered. An optimum condition has been suggested via numerical optimization of the desirability function with proper weights and importance of constraints. Vickers micro hardness testing was conducted to discuss structural changes in fused and heat affected zone.

Manufacturing industries aim for high quality production with decreased cost and time. To this purpose, optimization of the processing parameters is required, in order to reduce the machining time and match the quality standards. This study has been conducted to electrical discharge machining on Renè 108 DS. In the process, the electrode material is crucial for metal removal and tool wear, whose optimization usually leads to conflicting goals. Therefore, two electrode materials, graphite (Poco EDM-3) and copper-infiltrated-graphite (Poco EDM-C3) have been tested in a factorial plan including current, voltage, duty cycle and electrode polarity. The process is discussed in terms of material removal rate, tool wear rate, wear ratio and final surface roughness of the work-piece.

Ti-6Al-4V joints are employed in nuclear engineering, civil industry, military, and space vehicles. Laser beam welding has been proven to be promising, thanks to increased penetration depth and reduction of possible defects of the welding bead; moreover, a smaller grain size in the fusion zone is better in comparison to either TIG or plasma arc welding, thus providing an increase in tensile strength of any welded structures. In this frame, the regression models for a number of crucial responses are discussed in this paper. The study has been conducted on 1 mm thick Ti-6Al-4V plates in square butt welding configuration; a disk-laser source has been used. A three-level Box-Behnken experimental design is considered. An optimum condition is then suggested via numerical optimization with the response surface method using desirability functions with proper weights and importance of constraints. Eventually, Vickers microhardness testing has been conducted to discuss structural changes in fusion and heat affected zone due to welding thermal cycles.