Additive Manufacturing for Energy Applications IV: Characterization/Modeling
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS: Additive Manufacturing Committee, TMS: Nuclear Materials Committee
Program Organizers: Isabella Van Rooyen, Pacific Northwest National Laboratory; Indrajit Charit, University of Idaho; Subhashish Meher, Idaho National Laboratory; Kumar Sridharan, University of Wisconsin-Madison; Xiaoyuan Lou, Purdue University; Michael Kirka, Oak Ridge National Laboratory

Tuesday 8:00 AM
March 1, 2022
Room: 261B
Location: Anaheim Convention Center

Session Chair: Indrajit Charit, University of Idaho; Amey Khanolkar, Idaho National Laboratory; Xiaoyuan Lou, Purdue University

8:00 AM  Invited
Characterization and Testing of Additively Manufactured T-91 Ferritic/Martensitic Material: Peter Hosemann1; Jeffrey Bickel1; Calvin Lear2; Thomas Lienert3; Debroy Tarasankar4; Tuhin Mukherjee4; Osman El Atwani2; Stuart Maloy2; Shmuel Samuha1; 1University of California, Berkeley; 2Los Alamos National Laboratory; 3Optomec; 4Penn State University
    Additive Manufacturing has become a popular route to create difficult to produce geometries, hard to manufacture materials and a more just-in-time supply chain approach. Additive manufacturing is an integral part of the designer and material scientist toolbox today. The nuclear community is looking to utilize additive manufacturing for in-core components on nuclear materials. T-91 a ferritic-martensitic steel deployed and tested in fast reactor applications is considered for production via AM routes. This work utilizes laser based directed energy deposition methods to build T-91 components. We investigate orientation dependent microstructure and mechanical properties while evaluating the post-production heat treatment schedule needed to achieve desirable properties compared to wrought material. We find minimal orientation effects and rather beneficial properties compared to wrought material, enabling AM-T91 to be used in nuclear applications.

8:30 AM  
Optimization, Processing and Characterization of a Crack-resistant High-gamma Prime Superalloy for Additive Manufacturing in Power Generation Applications: Ning Zhou1; Stephane Forsik1; Austin Dicus1; Tao Wang1; Gian Colombo1; Andrew Holliday2; Michael Kirka3; Alexander Lunt4; Mario Epler1; 1Carpenter Technology Corporation; 2Carpenter Additive; 3Oak Ridge National Laboratory; 4University of Bath
     A nickel-base superalloy with 55-60 vol.% of gamma prime precipitate and a balance of hot cracking resistance, high-temperature mechanical properties and resistance to environmental damage was created to enable the redesign of critical turbine hot-gas-path components using additive manufacturing. The composition was optimized using a combination of thermodynamic modeling, high-throughput screening and experimental melting. Printing of complex parts with fine internal features show that the alloy can be processed by both selective laser and electron beam melting. Extensive characterization of the grain size, grain boundary composition, gamma prime distribution and gamma/gamma prime misfit was performed and the post-processing parameters were tailored for the alloy to generate 1200 MPa ultimate tensile strength and 1120 MPa yield strength at 760 degrees C. Oxidation resistance is provided by a dense layer of alumina that offers protection up to 1000 degrees C.

8:50 AM  
Effect of Microstructural Features on High Temperature Strength and Ductility of Selective Laser Melted Ni-base Superalloy: Masaki Taneike1; 1Mitsubishi Heavy Industries, Ltd.
    Additive manufacturing is an innovative manufacturing technology for realizing complex structural parts. In particular, the selective laser melting (SLM) can produce highly precise parts with high dimensional accuracy. We are working to improve gas turbine efficiency by applying the SLM to hot parts of our industrial gas turbine. Ni-base casting alloys are applied to the important hot parts of the gas turbine, but the Ni-base superalloys fabricated by SLM has various difficulties, especially for high temperature strength. In the SLM process, solidification progresses extremely fast, so very fine crystal grains are formed. In addition, due to the large temperature gradient and the high solidification rate, very fine columnar crystal grains are formed with strong anisotropy. In this research, the effect of microstructural features, such as grain shape and distribution of precipitates, on high temperature strength and ductility was investigated for Ni-base alloys similar to IN 939.

9:10 AM  
Relating Laser Scanning Effects to Cracking and Grain Structure of High-strength Superalloys: Marcus Lam1; 1Monash University
    Laser powder bed fusion (LPBF) can produce more efficient high-temperature components for energy-generating devices such as gas turbines, nuclear reactors, and heat exchangers. However, the range of suitable superalloys is still very limited due to their higher crack susceptibility and inferior microstructure produced in the LPBF process. Laser scanning as one of the main influencing will be discussed in this talk. The effects of laser parameters and scanning vector arrangement on several gamma-prime-strengthened superalloys will first be presented, followed by microscopy and process modeling analyses to explain the solidification conditions related to high angle grain boundary (HAGB) cracking in superalloys. The results suggest that a balanced consideration between cracking, productivity and deformation is required. This work can contribute to a better understanding of LPBF process relating to cracking, facilitating the broader application of superalloys in additive manufacturing.

9:30 AM Break

9:45 AM  
The Microstructure, Mechanical, and Physical Properties of Additively Manufactured 316H Stainless Steel Lattices: Carly Romnes1; Mohamed Aboukhatwa2; James Stubbins1; 1University of Illinois at Urbana-Champaign; 2Illinois Applied Research Institute
    Additive manufacturing (AM) can produce unique microstructures and geometries that cannot be manufactured conventionally. AM is used with many materials, but stainless steel alloys are some of the most widely used in industrial applications. For example, 316H SS is being considered for use in the Transformational Challenge Reactor (TCR), a 3D printed nuclear reactor. In this study, 316H SS lattice structures were additively manufactured using a GE Concept Laser Mlab 100R system. The phases and the chemical distribution of the AM 316H SS were determined using EBSD, XRD, and EDS. Additionally, the mechanical behavior and other properties were measured. Unexpectedly, we found that additively manufactured 316H SS has magnetic properties, something not typical of 316 stainless steels. We present observations about the microstructure, magnetic properties, and other behavior of AM 316H SS. This research will help inform future work on AM 316H SS for use in the TCR and beyond.

10:05 AM  
High Substrate Heating (up to 500 degC) in Laser Powder Bed Fusion of High-strength Superalloys and Its Implications: Marcus Lam1; 1Monash University
    Substrate heating is one of the viable measures to alleviate thermomechanical issues and, more importantly, microcracking in high-strength superalloys by laser powder bed fusion (LPBF). However, most research reported so far focused on LPBF systems of substrate temperature only up to 200 degC, a relatively low temperature for superalloys (<0.3 homologous temperatures). To improve the processibility and broaden the range of superalloys for LPBF, we explored the effects of substrate temperature up to 500 degC regarding the impacts on surface quality, deformation, and microstructure. Significant differences in crack susceptibility, phase precipitation, and microstructural deformation were observed, but the impact on surface roughness is moderate. The findings in this study will be explained in terms of metallurgy, microstructural analyses and process modelling. This presentation aims to provide scientific references for the benefits and issues of using high substrate temperature on superalloys by LPBF.

10:25 AM  
Light on: In Situ Investigation of Structural Transformation of Additive Manufactured Aluminum Alloys Using Synchrotron Methods: Fan Zhang1; 1National Institute of Standards and Technology
    Additive manufacturing (AM) of aluminum alloys represents a growth area in the Light Metals industry. Initially, AM aluminum alloy research was largely dominated by wrought aluminum alloys, especially Al-Si alloys with limited mechanical performance. Recent advancement in AM alloy design, which leverages the unique AM processing capability, creates exciting opportunities to design and deploy high-performance, heat-treatable AM aluminum alloys. A thorough understanding of the response of these alloys under different heat-treatment conditions is crucial for alloy optimization. Our recent work utilizing a world-leading synchrotron X-ray scattering facility has provided critical structural transformation insight for several AM aluminum alloys, including heat-treatable 5000 series aluminum alloys, customized 7000 series aluminum alloys, and custom-designed Al-Sc-Mn alloy with some best mechanical performances among AM aluminum alloys. We will highlight how our findings guide alloy optimization and underscore the impact of these characterization capabilities on the broad Light Metals community.

10:45 AM  
NOW ON-DEMAND ONLY – Identification of Nanoparticles Dispersion Mechanism in 316L Metal Matrix Composite Additively Manufactured by Hybrid Process of Jetting and Laser Powder Bed Fusion: Milad Ghayoor1; Omid Sadeghi1; Bryce Cox1; Ryan Doyle1; Joshua Gess1; Somayeh Pasebani1; 1Oregon State University
    Laser powder bed fusion (LPBF) is limited to producing monolithic alloy components. To produce metal matrix composites (MMC), the matrix is generally ball milled with second phase particles before the LPBF process; escalating the overall time, steps and cost of the manufacturing. In this work, an ethanol-based carrier containing Al13 nanoclusters, were deposited into the 316L powder bed via a Xerox print head mounted into a LPBF chamber. Then, the laser melts the MMC, dispersing nanoparticles into the matrix; eliminating the need of ball milling. Thermo-capillary Marangoni flow can disperse nanoparticles into the melt pool center. This approach enables us to selectively jet nanoparticles into the powder layers and change the composition of each layer; manufacturing the functionally graded alloys. Detailed characterization on 316L/Al2O3 nanocomposite using the proposed jetting approach revealed a similar microstructure and mechanical properties with nanocomposite produced with ball milling.

11:05 AM  
NOW ON-DEMAND ONLY - Design of Graded Transition Joints between Grade 91 Ferritic/Martensitic Steel and 347 Austenitic Stainless Steels with Non-linear Composition Variation Using Integrated Computational Materials Engineering (ICME) Approach: Rangasayee Kannan1; Yousub Lee1; Andres Rossy1; Brian Jordan1; Edgar Lara-Curzio1; Peeyush Nandwana1; 1Oak Ridge National Laboratory
    In this study, graded transition joints between grade 91 ferritic martensitic steel and 347 austenitic stainless steel with non-linear composition variation have been designed using ICME principles. Using inputs from classical mechanics, and CALPHAD to predict the C potential gradient a novel transition zone involving 5 different compositions with the width of each transition zone varying non-linearly has been proposed. Alongside the C chemical potential gradient predictions, CALPHAD was used to predict the coefficient of thermal expansion for the different compositions, which were used as inputs for the finite element model to predict the stress generated in the graded transition joint. It was found that the proposed transition zone produced a shallower C chemical potential gradient and lower stress during long-term aging than the conventional transition zone involving 10 compositions varying linearly.

11:25 AM  
Recent Advancements in SPPARKS Metal Additive Manufacturing Simulation Capabilities: Theron Rodgers1; Robert Moore2; John Mitchell1; Jeremy Trageser1; Daniel Moser1; Fadi Abdeljawad2; Jonathan Madison1; 1Sandia National Laboratories; 2Clemson University
    In recent years, metal additive manufacturing simulation capabilities in the SPPARKS microstructure simulation code have seen significant advancements. These include both refinements to physics models and computational capability improvements. Model improvements include the implementation of a finite-difference thermal conduction solver, material-dependent solidification behavior, and crystallographic texture prediction. Computational capability advancements include the ability to perform simulations on sub-volumes, utilize external thermal model results, and the implementation of novel heat sources, including a 3D spline-based melt pool and a jointed Rosenthal solution. Additionally, SPPARKS was recently migrated to a public GitHub repository to facilitate collaboration. This presentation will discuss these recent improvements, implications for AM process optimization, and future development plans. SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525