Additive Manufacturing: Solid-State Phase Transformations and Microstructural Evolution: Simulation and Modelling
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS: Additive Manufacturing Committee, TMS: High Temperature Alloys Committee, TMS: Phase Transformations Committee
Program Organizers: Bij-Na Kim; Andrew Wessman, University of Arizona; Chantal Sudbrack, National Energy Technology Laboratory; Eric Lass, University of Tennessee-Knoxville; Katerina Christofidou, University of Sheffield; Peeyush Nandwana, Oak Ridge National Laboratory; Rajarshi Banerjee, University of North Texas; Whitney Poling, General Motors Corporation; Yousub Lee, Oak Ridge National Laboratory
Tuesday 8:30 AM
March 16, 2021
Room: RM 5
Location: TMS2021 Virtual
Session Chair: Andrew Wessman, The University of Arizona; Yousub Lee, Oak Ridge National Laboratory
8:30 AM Invited
Fundamental Investigation of Multi-Principal Element Alloy (MPEA) Design and Processing Research to Explore Additive Manufacturing (AM) Effects: Iver Anderson1; Emma White1; Duane Johnson1; Timothy Prost1; Ralph Napolitano1; Andrew Kustas2; Nicolas Argibay2; 1Iowa State University / Ames Laboratory; 2Sandia National Lab-NM
Results are reported that span the spectrum between advanced alloy theory prediction of a MPEA composition, 19Al-19Fe-19Ni-19Co-19Cr-5Cu (at.%), to specific crystal structure selection and verification experiments that range from chill casting to powder synthesis by close-coupled gas atomization (CC-GA) to AM building by directed energy deposition (DED), and through post-build heat treatment of the sample. Alloy design and modeling was based on an all-electron theory, addressing chemical disorder, where valence-electron concentration is a key determinant for tuning elemental concentrations. “Spider” plots based on binary, piece-wise formation energies narrowed the MPEA composition. Microstructural analysis verified alloy buttons from arc melting/chill casting as single as-solidified phase. Gas (Ar) atomization synthesized the quantity and size range of feedstock powder needed for DED. Dense AM builds were performed by laser engineered net-shaping. Critical structural, mechanical, and microstructural analysis of the material forms are described. Funded by USDOE-EERE-AMO program through Ames Lab contract no. DE-AC02-07CH11358.
9:00 AM
CALPHAD Based Thermo Kinetic Modeling for Additive Manufacturing (AM): A Case Study for Fusion Based and Supersolidus Liquid Phase Sintering During Binder Jet: Rangasayee Kannan1; Peeyush Nandwana1; 1Oak Ridge National Laboratory
The aim of this talk is to demonstrate the use of thermo-kinetic models for understanding the underlying phase transformations in laser powder bed fusion and binder jet additive manufacturing, technologies on the opposite side of the spectrum. While the former results in far from equilibrium conditions, the latter takes place at near thermodynamic equilibrium. As a case study, the thermodynamic concepts will be applied to laser powder bed fusion of grade 300 maraging steel to predict precipitation and austenite reversion during post-fabrication aging heat treatments, and to H13 tool steel manufactured using binder jet AM, to predict phase transformations during sintering, hot isostatic pressing, and solutionizing and tempering heat treatment. Results highlight the fact that an ICME approach can be used to decide the optimal temperature/time combinations for post-AM heat treatments, thereby reducing the time/energy/cost associated with excessive experimentation.
9:20 AM
Phase Field Modeling of Powder Densification in Sintering: Rui Dong1; Wenda Tan1; 1University of Utah
Multiple additive manufacturing processes (e.g., binder jetting, fused deposition modeling) can 3D print green parts of complex geometries that must be densified through sintering. The sintering process is a critical step that determines the final microstructure (i.e., porosity, micro-cracking, and grain texture) and properties of the printed parts. In this work, we present a Phase-Field model to simulate the powder densification and grain growth during sintering. The model uses thermodynamic descriptions from the CALPHAD database and the dimensional coefficients to calculate the energy density function for the material(s) to be simulated. The model is validated against experimental results and then used to investigate the effect of green density on the part shrinkage and pore/cracking formation during sintering.
9:40 AM Invited
Probabilistic Machine Learning Assisted Study of Directed Energy Deposited Alloys: Soumya Nag1; Yiming Zhang1; Sreekar Karnati1; Lee Kerwin2; Eric MacDonald3; Neil Johnson1; Sathyanarayanan Raghavan1; Dora Cheung2; Alex Kitt2; Changjie Sun1; Genghis Khan1; Chris Williams4; Thomas Broderick5; Mark Benedict5; Brandon Ribic6; 1GE Research; 2EWI - Buffalo Manufacturing Works; 3Youngstown State University; 4GE Aviation; 5Air Force Research Laboratory; 6America Makes
Additive Manufacturing is truly a “complexity for free” fabrication process. However, the complex interaction of design, materials and manufacturing often lead to long iterative evaluation cycles. Therefore, materials and manufacturing strategies need to be aligned with Materials Genome Initiative to develop, produce and deploy high throughput components. To achieve this, coupling experimental and computational tools, as well as application of novel processing techniques are essential. In the current study, powder blown Directed Energy Deposition (DED) AM modality was employed to fabricate structural Titanium and Nickel alloys. The overarching goal was to set up subscale build DOEs that encompass critical feature and/or compositional space. Subsequently, physics-based model that generated response surfaces was used to predict and in turn optimize build pathways tailored toward targeted build strategies. It is important to note that this paradigm may be universally applied to materials and AM modalities beyond the current scope of this work.
10:10 AM
Prediction of Microstructure and Phase Evolution during Multi-track, Multi-layer Directed Energy Deposition of H13: Neil Bailey1; Christopher Katinas1; Yung Shin1; 1Purdue University
During additive manufacturing processes, the resultant microstructure can exhibit significant variations. We present combined numerical models developed for predicting microstructure and mechanical properties during laser-based additive processes. A validated, physics-based computational fluid dynamics model with an improved level-set method is built to simulate the heat/mass transport and the dynamic evolution of the molten pool surface on the macro-scale. Based on the three dimensional temperature and cooling rates calculated during the solidification processes, the resultant microstructural evolution is predicted using a computationally efficient novel cellular automata-phase field model during multi-track and multi-layer laser-based deposition processes of multi-component alloys such as H13 alloys. In addition, the solid state phase transformation due to repeated heating and cooling of solidified regions during multi-track and multi-layer deposition is also modeled. The predicted microstructures and phase distributions are used to predict resultant microstructure, hardness and residual stresses, which are validated by the experiments.
10:30 AM
New Insights on Cellular Structures Strengthening Mechanisms and Thermal Stability of L-PBF Stainless Steel 316L: Thomas Voisin1; Jean-Baptiste Forien1; Aurelien Perron1; Sylvie Aubry1; Nicolas Bertin1; Amit Samanta1; Alexander Baker1; Y. Morris Wang1; 1Lawrence Livermore National Laboratory
In this work, we investigate the deformation mechanisms and thermal stability of L-PBF 316L SS. Our main results show that the high density of entangled dislocations inside cell walls have a higher tendency to dissociate, forming wider stacking faults while many oxide precipitates are confined inside cell walls. Both features act as barriers to moving dislocations upon plastic deformation and contribute to the high strength. Our dislocation dynamic simulations indicate that segregated particles are effective in blocking dislocations locally, helping the formation of dislocation cells and participating to the material strengthening. Our characterizations using electron microscopy, synchrotron X-ray diffraction, CALPHAD simulations, and tensile testing of post-processed annealed materials reveal three heat treatment zones between 600 and 1200oC where the structure-property relationship can be tuned.This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
10:50 AM
Process Dependent Nanoscale Vanadium Clustering within Martensite Laths in Laser Powder Bed Fused Additively Manufactured Ti6Al4V: Mangesh Pantawane1; Sriswaroop Dasari1; Srinivas Mantri1; Rajarshi Banerjee1; Narendra Dahotre1; 1University of North Texas
The repetitive and rapid nature of thermal (heating/cooling) cycles experienced in solid-state Ti6Al4V additively manufactured by laser powder bed fusion (LPBF-AM) can partially temper the non-equilibrium state of martensitic laths. The homogenous distribution of nanoscale vanadium clustering forms within the martensitic laths of LPBF-AM Ti6Al4V and can be rationalized through thermo-diffusion kinetics derived from computational multiphysics model. The computational model predicts the extremely rapid thermokinetics associated with thermal cycles experienced at any given location of LPBF-AM Ti6Al4V. The numerically estimated effective V diffusion length of 6.61 nm indicates kinetic-limited diffusion resulting in V nanoclusters and further matches with atom probe tomography evaluations of half the inter-cluster spacing of 7 nm.