Additive Manufacturing of Large-scale Metallic Components: Steels
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS: Additive Manufacturing Committee
Program Organizers: Sneha Prabha Narra, Carnegie Mellon University; Sougata Roy, University of North Dakota; Andrzej Nycz, Oak Ridge National Laboratory; Yousub Lee, Oak Ridge National Laboratory; Chantal Sudbrack, National Energy Technology Laboratory; Albert To, University of Pittsburgh

Tuesday 8:00 AM
March 1, 2022
Room: 263A
Location: Anaheim Convention Center

Session Chair: Sougata Roy, University of North Dakota

8:00 AM  
Correlating Microstructure with Thermal Models in Wire-arc Additive Manufacturing of Mild Steel: Mark Anderson1; Jeffrey Shield1; Prahalada Rao1; Janmejay Kulkarni2; Alex Riensche1; Surya Kumar2; 1University of Nebraska - Lincoln; 2Indian Institute of Technology Hyderabad
    Wire-arc additive manufacturing (WAAM) allows for high deposition rates with low materials cost, providing a feasible route to production of large-scale parts. Some issues with the high deposition rates include the heat variances seen within the part due to the speed of processing. By controlling the thermal evolution the part experiences, we can tailor the microstructure of the part. In this study, we compared the microstructural evolution with thermal characteristics both measured and computed using graph theory for ER70S-6 wire. The goal is to predict microstructural evolution based on graph theory models. The study compared thin wall and trapezoid geometries with varying inter-bead wait times. Microstructurally, the cooling rates were analyzed by comparing the interlamellar spacing of the pearlite phase. The faster cooling rates showed a finer pearlite with less interlamellar spacing while the opposite is observed for slower cooling, and were consistent with the predicted and observed thermal characteristics.

8:20 AM  
Characterization of a Large-scale 316L Body Produced with High Deposition Rate Wire Arc Directed Energy Deposition: Luc Hagen1; Zhenzhen Yu1; Stephen Tate2; Andrezj Nycz3; Luke Meyer3; Jonah Klemm-Toole1; 1Colorado School of Mines; 2EPRI; 3Oak Ridge National Labratory
    The use of wire-arc directed energy deposition (WA-DED) or wire arc additive manufacturing (WAAM) is being considered as a fabrication method for pressure components within nuclear power plants. This would allow for onsite construction of replacement parts, decreasing plant down time and preventing millions of dollars in losses. However, updates to ASME code are needed to use WA-DED to construct large 316L stainless steel pressure retaining components. In this presentation, we discuss our work characterizing a large-scale (>200 lb) 316L pressure retaining valve body built with a high deposition rate pulsed spray transfer weld mode. Microstructural and mechanical properties were studied with tensile testing, Charpy impact testing, microscopy, and EBSD. Additionally, the impact of defects on WA-DED components was studied by introducing controlled defects into small-scale WA-DED builds. From these results we discuss the current state of WA-DED of 316L and determine the feasibility of using WA-DED components within powerplants.

8:40 AM  Cancelled
Effects of Interlayer Dwell Time on Microstructure of Maraging Steel 250 Thin Walls Fabricated via Wire Arc Additive Manufacturing: Yao Xu1; Brajendra Mishra1; Sneha Prabha Narra2; 1Worcester Polytechnic Institute; 2Carnegie Mellon University
    The high energy input in wire arc additive manufacturing leads to in-situ heating of the previously deposited layers, which in turn, can have a notable effect on the as-fabricated microstructure of age hardenable materials. Hence, a comprehensive understanding of in-situ thermal cycles and heat accumulation on the microstructure evolution and resulting properties can be a key to optimal process design. In this work, thin walls were deposited with different interlayer dwell times using maraging steel 250. Hardness testing and comprehensive microstructure characterization showed anisotropy along the wall height and different levels of precipitation hardening due to different dwell times. The kinetics of precipitation in the as-fabricated material was quantified via temperature-time-hardness mapping. Strong Ni, Ti, and Mo partitioning during solidification were found to affect the aging behavior. This work can serve as a basis to investigate the possibility of microstructure tailoring during wire arc additive manufacturing of maraging steel 250.

9:00 AM  
NOW ON-DEMAND ONLY - The Effect of Preheating Substrate on the Microstructure and Mechanical Properties in Laser Deposited Martensitic Steel: Md Mehadi Hassan1; Madhavan Radhakrishnan1; Thomas Lienert2; Osman Anderoglu1; 1University of New Mexico; 2Optomec Inc.
    The traditional manufacturing approach to produce engineering components can have a high energy cost, longer delivery times, and specific geometries that may be unattainable. The Direct Energy Deposition(DED) offers excellent capabilities of fabrication with metal complex geometries, repair, and large-scale additive fabrication among all AM processes. This work focuses on the fabrication of AISI 420 martensitic steel using DED for the application of the aerospace, automotive, and medical industries. AISI 420 martensitic steels(0.4%C,12.7%Cr,in wt.%) were successfully deposited onto the preheating (110⁰Cand190⁰C) 316L substrates. The process produced a near-fully dense deposit. The cross-sectional examination by electron microscopy and XRD confirms dual-phase microstructure of martensite and austenite. Preliminary mechanical characterization by micro-Vickers hardness tests shows a uniform hardness trend across the build. The talk would explore the effects of processing heat input and post-processing heat treatment conditions on the evolution of microstructure, phase transformation, and mechanical performance of 420 martensitic steel.

9:20 AM Break

9:40 AM  
Wire Arc Additive Manufacturing of Stainless Steels: Kinetics Modeling of Phase Transformations Using Differential Scanning Calorimetry: Md Moniruzzaman1; Ali Nasiri2; Amir Hadadzadeh1; 1University of Memphis; 2Dalhousie University
    Metal additive manufacturing (AM) is known as a breakthrough for the fabrication of components with enhanced mechanical properties. The AM processes are categorized into two main groups: powder bed fusion (PBF) and directed energy deposition (DED). The deposition rate in the DED processes is substantially higher than that in the PBF processes and the build volume is unconstrained. Therefore, large AM components could be fabricated using the DED processes within a reasonable period. One promising DED process is wire arc additive manufacturing (WAAM). In this study, SS410S and Fe-Cr-Ni-Al CX stainless steels were fabricated through WAAM. Both materials were characterized using differential scanning calorimetry (DSC) to analyze their phase transformations, including austenite reversion (in both) and precipitation (in CX). Both continuous heating and isothermal DSC curves were used to develop kinetics models. The findings of this study will provide significant insight into developing optimum heat treatment cycles for these materials.

10:00 AM  
NOW ON-DEMAND ONLY - A Comparative Study of Deformation Mechanisms in 316L Stainless Steel Fabricated by Additive and Additive + Subtractive (Hybrid) Manufacturing: Rangasayee Kannan1; Peeyush Nandwana1; Christopher Fancher1; Thomas Feldhausen1; 1Oak Ridge National Laboratory
    We have shown that hybrid manufacturing has the potential to fabricate 316LSS parts with superior strength than the wrought materials and with a ductility higher than additive manufacturing and comparable to wrought materials. In this presentation, the effect of texture and residual stresses on the mechanical performance of 316L stainless steel fabricated by additive and hybrid manufacturing will be comparatively investigated using advanced characterization techniques and strain hardening analysis. The effect of residual stresses and texture on twin generation in the as-fabricated component and the effect of twins in the as-fabricated component on the deformation mechanism will be discussed. Using the results, the higher strength and elongation of hybrid manufactured 316L components will be rationalized.