Session: 03-08-01: Computational Modeling and Simulation for Advanced Manufacturing

Paper Number: 111920

111920 - A Finite Element Modeling Approach to Dwell Time Optimized Maraging 250 Parts for Wire Arc Directed Energy Deposition 

Wire arc directed energy deposition (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. This process can produce large components at a high deposition rate causing large amounts of heat to pass through the part into the substrate. 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 Interpass temperature is a welding metric commonly used in industry to improve interlayer fusion and microstructural development for each deposited weld bead by maintaining a minimum temperature that must be reached prior to the next bead being deposited. This method maintains a similar cooling rate between subsequent layers, often leading to an increase of martensitic phase volume fraction and more consistent grain morphology. 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. Additionally, the output variables will be compared in each simulation across the start, middle, and end cross sections to determine the optimum location for measuring the interpass temperature for process control feedback. 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.

Presenting Author: Matthew Register Mississippi State University

Presenting Author Biography: Matthew Register is a third year PhD student in the department of mechanical engineering at Mississippi State University. He is member of the computational mechanics and materials laboratory (CMML) where the focus of his work uses finite element modeling to understand the process-structure-property-performance relationship of wire arc directed energy deposition process.

Using the thermomechanical modeling framework, Matthew has previously simulated a wide variety of print process parameters such heat input, print strategy, material property input, and dwell time for residual stress and distortion minimization in as-built parts with the goal of understanding the process-property relationship involved in wire arc directed energy deposition.

Matthew's current work is focused on determining resultant 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. This work utilizes an array of FE simulations to provide a preliminary process-structure relationship necessary for determining the success of wire fed DED builds.

Authors:

Matthew Register Mississippi State University
Logan Betts Mississippi State University
Matthew Priddy Mississippi State University