Wire + Arc Additive Manufacturing (WAAM) is a promising technology for the manufacturing industry due its capacity to reduce material waste by up to 90% in certain applications whilst also providing a means of production for large-scale (<1m) metal structures with high deposition rates of up to 4kg/hr [1]. These comparatively higher rates of deposition and large build volumes allow WAAM to fulfil manufacturing roles which its counterpart technologies such as Powder Bed Fusion would struggle to perform in an economical manner [1], [2]. The Automotive and Aerospace sectors are looking into WAAM as a prospective solution to fabricate large scale, medium complexity components with additional time and cost savings when compared to current subtractive and formative manufacturing methods [3]. Due to the energy sources employed, WAAM suffers from similar defects observed in welding such as porosity, distortion, residual stresses, hot cracking etc. [4], [5]. This research will investigate the parameter settings and process controls (e.g. travel speeds and cooling rates) of WAAM Via Cold Metal Transfer (CMT) which can improve the mechanical properties, microstructure and geometrical quality of WAAM Mild Steel single and multilayer specimens whilst minimising the presence of aforementioned defects. Testing will evaluate the tensile and flexural strength of machined specimens, fatigue life and microhardness throughout the multilayer deposits to characterise the effects of varying heat, current and voltage inputs, deposition strategies, inter-layer cooling rates and travel speeds.
