Monitoring and Optimizing Arc Length to Tailor Microstructure and Mechanical Property of Magnesium Alloy via Wire-Arc Directed Energy Deposition

Arc length, as a key process parameter of wire-arc directed energy deposition (WA-DED), affects quality, microstructure, and mechanical properties of the deposited layer.In this work, an industrial charge-coupled device camera was used to monitor the arc length in the WA-DED process, and a novel arc length detection strategy was developed.Four kinds of arc lengths, such as 4 (AM-4), 6 (AM-6), 8 (AM-8), and 10 (AM-10) mm, were used to prepare AZ31B magnesium alloy, and the effects of arc length on the microstructure and properties were studied in depth.Experimental findings indicate that the deposited layer exhibits superior surface quality at arc lengths of 6 and 8 mm.Compared with the AM-8 sample, the AM-6 sample has finer grains and less porosity.The tensile test results at 25 ℃ and 200 ℃ show that the AM-6 sample exhibits better strengthplasticity synergy than the 8 mm sample.The fine grains and less porosity caused by the reduction of arc length are the main reasons for the increase of plasticity.