A Finite Element Modeling Approach to Dwell Time Optimized Maraging 250 Parts for Wire Arc Directed Energy Deposition

Abstract

Abstract Wire arc directed energy deposition (WA-DED) is a metal based additive manufacturing (AM) process which utilizes an electric arc welding source to melt wire in a layer-by-layer manner Continuous thermal expansion and contraction, associated with uneven cyclic heating and cooling, leads to mechanical property heterogeneity as well as the formation of residual stresses and distortion in wire fed DED built parts. To control the interpass temperature during deposition, process parameters such as print strategy, heat input, and dwell time are often tested through an extensive experimental process parameter examination; however, finite element (FE) modeling provides the ability to simulate a variety of process parameters quickly, saving time and money. FE modeling has been shown to improve final part quality by predicting the thermal and structural response in as-built parts based on a variety of wire fed DED process parameters. This work will present a method for determining reasonable part quality metrics based on the variance in simulated cooling rates, max temperatures, and interpass temperatures as a function of heat input, print strategy, and dwell time. A design of experiments will be performed in Abaqus 2019 for a 10-layer thin wall build with differing heat inputs, print strategies, and fixed dwell times. The FE simulated cooling rates, interpass temperatures, and max temperatures will be compared with known martensite and austenite phase transition temperatures of maraging grade 250 (M250) to determine the optimum welding parameters needed to improve the part quality. Using this approach, a resultant part can be made with optimum process parameters with tailored control of the max temperature, cooling rate, and interpass temperature. This framework utilizes an array of FE simulations to provide a process-structure relationship necessary for determining the performance success of wire fed DED builds.