Soft-magnetic properties of wire-arc additively manufactured Fe–49Co–2V alloy improved through post-deposition heat treatment

Abstract

A wire-arc additive manufacturing (WAAM) process was adopted to prepare Fe–49Co–2V alloy. A commercial plasma-transferred arc (PTA) welding torch coupled with a computer numerically controlled (CNC) locomotor was used to deposit the alloy in the form of a simple wall. The soft-magnetic properties of the deposited alloy were evaluated by measuring the variation of magnetisation versus applied field strength. The as-deposited alloy was also heat-treated at various temperatures to improve different magnetic properties, such as saturation magnetisation, remanence, coercivity and energy/power loss. It was found that an annealing treatment at 1000 °C for 4 h improves coercivity, magnetic remanence, and power loss by decreasing them by 61 %, 50.5 %, and 38.5 %, respectively, from the as-deposited condition. A correlation was also established between microstructure and magnetic properties. It was observed that the alloys, both as-deposited and heat-treated, do not follow Soumail's model established between coercivity and grain size. It has been shown that the presence of Type II residual stress in the lattice, as well as small particles of vanadium oxide scattered across the matrix, is the reason for such discrepancy.