| Abstract Scope |
Performance optimization in large format metal additive manufacturing of high strength steels (HSS) is required to take advantage of increasingly complex mechanical component designs. Conventional additive manufacturing (AM) parameter development for HSS uses a trial-and-error approach that is time, material, labor, and cost-prohibitive. Importantly, there is a limited understanding of in-situ tempering induced by the layer-by-layer AM process that occurs, especially in HSS with elevated carbon content. This work aims to demonstrate the optimization of process-microstructure-properties (PMP) through a computational design of experiments (CDoE) framework for wire-arc directed energy deposition (WA-DED) of a new high strength steel (HSS). The CDoE framework integrates design of experiment (DoE), finite element analysis (FEA), thermodynamic and kinetic modeling, and post-processing modules to achieve this objective. The post-processing module utilizes PMP relationships consisting of a continuous cooling transformation diagram representative of WA-DED and multiple reheat tempering response relationships of the studied HSS. Predicted microstructure and hardness maps output by the CDoE illustrates areas reheated to supercritical and intercritical peak temperatures, as well as areas efficiently tempered by subcritical reheats. The effect of in-process multiple reheat tempering is explored via a range of simulated WA-DED process parameters and predicted microstructure and hardness. Optimal WA-DED process windows are determined by quantifying the areas of high and low tempering response. Production, hardness mapping, and metallurgical characterization of HSS test builds will validate optimal WA-DED process windows. |