Experimental investigation into wire ARC additive manufacturing of aluminium 5356 alloy part and it’s post processing by laser nitriding

Abstract

Aluminium alloys find wide-ranging applications in the different industries due to their lightweight nature, high specific strength, excellent corrosion resistance, good damping capacity, high machinability, and good strength-to-weight ratio. Wire-arc additive manufacturing (WAAM) is well-suited process for application in a variety of sectors since it can produce big, reasonably complicated parts at minimal investment, operating expenses and high deposition speed and efficiency. Different process parameters like stand off distance, feed, voltage, and cooling time play a vital role in controlling the quality of WAAM deposited parts. However, the additively manufactured component requires different post processing techniques to enhance the mechanical and tribological properties. The present study deals with the parametric optimization of process variables of WAAM for fabricating parts of aluminium 5356 alloy based on mathematical modelling using experimental data as per Box Behnken design of experiments. Moreover, the single and multi- objective optimization of the responses were also performed using desirability function analysis to obtain an optimal set of process variables. On the optimal parametric setting, aluminium alloy walls were deposited and different mechanical testing like tensile testing and micro-hardness testing are performed on it. The additively manufactured samples at optimal parametric setting are treated with selective area nitriding to reduce the coefficient of friction, wear volume and also to enhance the micro-hardness. The impact of laser nitriding process parameters such as laser intensity, scanning speed, and N2 gas flow, on the surface hardness, contact angle and tribological properties of wire-arc additively manufactured Al alloy part has been investigated. The laser nitriding significantly improved the surface hardness and reduced the coefficient of friction and wear volume. The laser interaction resulted in a change of the surface from hydrophilic to hydrophobic which helps to reduce the bio-fouling and maintaining the smooth operation of the marine components.