<p>Interlayer arc treatment was introduced in WAAM-TIG (wire arc additive manufacturing utilising tungsten-inert-gas) to improve the mechanical properties of copper. Copper was chosen for this experimental research considering its application in heat exchanges, which require high mechanical strength along with excellent thermal properties. This interlayer arc treatment remelts the already deposited layer by utilising arc energy. This arc treatment was found to minimise the formed porosity significantly due to the combined effect of arc and recoil pressure, and promoted the grain refinement. The effect of this arc treatment was analysed on mechanical properties such as hardness, tensile, compressive, and flexural/bending strength along scan and build directions. Further, the mode of arcing was also altered from continuous to pulse mode. It was found that the arcing in pulse mode enhances the process efficiency along with a significant improvement in mechanical properties. The hardness was found to be improved by ~ 43% with the interlayer arc treatment. Overall, an increase of tensile yield strength ~ 49% and ~ 44%, ultimate tensile strength ~ 46% and ~ 51%, compressive yield strength ~ 46% and ~ 38%, and ultimate compressive strength ~ 63% and ~ 66% was observed, compared to as fabricated samples in scan and build directions, respectively.</p>