Additive Manufacturing: Qualification and Certification: Microstructure and Properties
Sponsored by: TMS Additive Manufacturing Committee, TMS: Mechanical Behavior of Materials Committee, TMS: Nanomaterials Committee
Program Organizers: Faramarz Zarandi, RTX Corporation; Jacob Hochhalter, University of Utah; Douglas Wells, NASA Marshall Space Flight Center; Richard Russell, NASA Kennedy Space Center; Mohsen Seifi, ASTM International/Case Western Reserve University; Eric Ott, GE Additive; Mark Benedict, Air Force Research Laboratory; Craig Brice, Colorado School Of Mines; J Hector Sandoval, Lockheed Martin
Monday 2:00 PM
November 2, 2020
Room: Virtual Meeting Room 8
Location: MS&T Virtual
Session Chair: Jacob Hochhalter, University of Utah; Richard Russell, NASA Kennedy Space Center
2:00 PM Cancelled
Microstructure to Aerostructure: Retrospectives and Microstructural Challenges in Industry for Titanium Additive Manufacturing: Andrew Baker1; Matthew Crill1; Fatmata Barrie1; 1The Boeing Company
Several successes of implementation of titanium additive manufacturing (AM) for aerostructure in defense, space, and commercial realms have shown feasibility of its viability as a complimentary advanced manufacturing method to other advanced and traditional methods. However, the widespread adoption of titanium additive manufacturing for aerostructure has yet to be realized due to the challenges associated with robustness and stability of the processes, microstructural challenges of processing alloys not designed for AM, and the lack of the appropriate standards and infrastructure to support the deployment of the technology. These challenges manifest themselves in the qualification and certification pathways required for flightworthy structure. This presentation will focus on the microstructural challenges and opportunities for continued incremental insertion. The challenges and opportunities will be framed with a brief retrospective of successful implementations at Boeing, as well as collaborative government-funded efforts to address a future-state of modeling assisted qualification pathways.
2:30 PM
A Multi-Sensor Comparative Study for Fatigue Prognosis of Additively Manufactured Metallic Specimens: Susheel Dharmadhikari1; Asok Ray1; Amrita Basak1; 1Pennsylvania State University
The research presents a novel methodology for fatigue prognosis of additively manufactured AlSi10Mg specimens by comparing two timeseries signals from ultrasonic and strain sensors and two sets of image sequences from confocal and digital microscopes. Ultrasonic investigation is used extensively to identify cracks. Similarly, hysteresis curves are known to contain the cumulative damage information indicating failures. Both sets of data work successfully in segregating cracked and uncracked specimens. Initiation of crack, on the other hand, cannot be clearly identified through these data sets due to seemingly insignificant changes in the signals. In such situations, magnified images from confocal and digital microscopes capture minute cracks and help in identifying these crack-initiation-windows in the time series signals. Using pattern recognition techniques, these windows can then be processed to identify unique features that correspond to crack initiation. With accurate calibration, the framework finds its direct application in online fatigue prognosis.
2:50 PM
Simulation of the Effect of Texture on Anisotropy in SLM-Produced IN718 Microstructures: Wesley Tayon1; Saikumar Yeratapally2; Joseph Pauza3; Anthony Rollett3; Jacob Hochhalter4; 1NASA Langley Research Center; 2National Institute of Aerospace; 3Carnegie Mellon University; 4University of Utah
As the aerospace community seeks to use additively manufactured components, it is crucial to understand the role crystallographic texture has on part performance. Strong textures are associated with highly anisotropic material response. Often, thermal processing conditions in additive manufacturing lead to highly elongated grains with a dominant texture. Selective laser melting (SLM) is perhaps one of the most common metal additive manufacturing methods capable of producing lower cost, complex part designs. The SLM process offers the capability to 3D print nickel-based superalloys for applications such as high-temperature engine components. In this study, a kinetic Monte-Carlo grain growth and texture simulation code (SPPARKS), was used to simulate Inconel (IN) alloy 718 microstructures across several SLM build conditions. The synthetic IN718 microstructures were input into both crystal plasticity finite element and fast Fourier transform models to assess the impact of texture and grain morphology on anisotropy at the grain scale.
3:10 PM Invited
Reducing Anisotropic Deformation of LPBF Inconel 718 for Applications in Extreme Conditions: Nadia Kouraytem1; John Varga1; Benham Amin-Ahmadi2; Raphael Chanut1; Ashley Spear1; Owen Kingstedt1; 1University of Utah; 2Colorado School of Mines
Inconel 718 (IN718) parts manufactured using manufacturer recommended processing parameters using laser powder bed fusion (LPBF) exhibit columnar microstructures that grow along the build direction. Subsequently, as-built and direct-aged IN718 specimens were shown to deform anisotropically under quasi-static and high-strain rate uniaxial compression when loaded in the sweep or transverse direction. In this investigation, a non-conventional short-time-scale recrystallization post-processing heat treatment is presented to reduce anisotropy in the deformation of LPBF IN718 specimens extracted from a large additively manufactured volume of material. However, the recrystallized samples surprisingly show an increase in the yield strength compared to the as-built condition. The improved yield strength of the material is related to the underlying microstructure resulting from the heat treatment. The outcomes of this study are important for qualification of structural parts where reduced anisotropy combined with improvement in the yield strength are necessary in the case of loading under extreme conditions.
3:40 PM
Pore Formation in Laser Powder Bed Fusion Inconel 718 through Multiphysics Modeling: Qian Chen1; Seth Strayer1; Albert To1; 1University of Pittsburgh
Laser powder bed fusion (L-PBF) is an important additive manufacturing technology which allows the direct fabrication of metal parts with intricate internal structure in a layer-by-layer manner. Despite the wide industrial applications, LPBF process still suffers from a variety of issues in the fabricated part quality where porosity generation is a key issue not well studied and tackled. In this study, a multiphysics model is developed to study the formation and evolution of porosity for Inconel 718 in LPBF. Before laser scanning simulation, powder particle distribution for each layer is obtained from the powder lay and spread simulation by discrete element method (DEM). Lack of fusion pores have been found with a larger hatching space and can be eliminated with smaller hatching space. Moreover, it is observed that pore formation is tightly associated with its neighboring powder particle distribution which can be attributed to denudation.