Additive Manufacturing: Materials Design and Alloy Development III -- Super Materials and Extreme Environments: Poster Session
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS: Additive Manufacturing Committee
Program Organizers: Behrang Poorganji, Morf3d; Hunter Martin, HRL Laboratories LLC; James Saal, Citrine Informatics; Orlando Rios, University of Tennessee; Atieh Moridi, Cornell University; Jiadong Gong, Questek Innovations LLC

Tuesday 5:30 PM
March 16, 2021
Room: RM 3
Location: TMS2021 Virtual


Comprehensive Study on Creep Performance of Selective Laser Melted Inconel 718 through Post Heat Treatment and Microstructure-based Modelling: Shun Wu1; 1Monash University
    The Inconel 718 (IN718) is one of the most widely used Ni-based superalloy in additive manufacturing, due to its high weldability and high temperature strength. However, recent attempts in additively manufacturing IN718 by the Selective Laser Melting (SLM) technique however reported much inferior creep properties comparing to the conventional IN718. This particularly limited the implementation of SLM in aerospace application, and more in-depth research on how to improve the creep performance of SLM IN718 is urgently needed. In this study, the as-SLMed IN718 were post-heat treated to obtain different microstructure features and their creep properties were compared. Meanwhile, a microstructure-based creep model was built to understand the creep mechanisms for SLMed IN718. This study provides a comprehensive understanding on microstructure evolution under different heat treatment conditions and how different factors (grain structure, Laves phase, carbides) affect the creep performance of SLMed IN718.

Design and Development of Multi-Microlattice Structures for Improved Mechanical Behavior: Bikram Sahariah1; Akshay Namdeo1; Prasenjit Khanikar1; 1Indian Institute of Technology Guwahati
    Microlattices are a class of man-made structures that are made of an interconnected network of struts, with advantages like high strength to weight ratio, outstanding energy absorption and negative Poisson’s ratio. Recent developments in the field of additive manufacturing of metals and polymers have enabled the fabrication of micro-architectures with tailorable properties with ease. In this work, novel multi-microlattice structures composed of multiple lattice unit cell geometries are designed and fabricated by additive manufacturing technique, and the quasi-static compressive behavior is studied. The multi-microlattice structures are found to excel in terms of compressive strength and energy-absorbing capability when compared to single microlattice. The modes of deformation of the multi-microlattice structures are studied, and buckling of the struts is found to be the prominent deformation mechanism. Along with experimental investigation, finite element analysis using Abaqus/Explicit is also carried out.

Influence of Heat Treatments on the Dynamic Behavior of an Additively Manufactured IN718 Alloy: Saurabh Sharma1; Kiran Solanki1; 1Arizona State University
    Additive manufacturing (AM) provides an opportunity to produce complex parts that are near net shapes, such as turbine blades, turbopumps and diffuser cases. However, a detailed investigation on mechanical behavior under varying strain rates is critical for broader applicability. Therefore, in this work, IN718 is used as a model material system to uncover the influences of post-heat treatments on the dynamic behavior of AM processed samples. Tensile and compressive quasi-static and high strain tests were performed and results were investigated depending on build orientations as well as precipitated phases. The microstructural investigation was performed on pre and post deformed samples to verify the effect of precipitated phases. Results show that mechanical behavior under varying strain rates of AM samples is very similar to those of wrought alloys with a specific heat treatment.

Mechanical Performance of Additively Manufactured Metallic Tetrahedral Microlattice Structure: Akshay Namdeo1; Bikram Sahariah1; Prasenjit Khanikar1; 1Indian Institute of Technology Guwahati
    Since the emergence of advanced manufacturing technologies like additive manufacturing, fabrication of complex microlattice structure has become possible. The high energy absorbing capabilities and higher strength to weight ratio of the microlattice has contributed to its wide range application in lightweight and high-energy absorbing structures. With relative density being the most important factor for the mechanical characteristics of microlattice, the geometry of the microlattice unit cell also contributes significantly toward the deformation behavior of the microlattice. In this study, the mechanical performance of metallic tetrahedral microlattice structures, which have not been previously studied, is investigated over a range of relative densities and strut diameters. The quasi-static compression test results have been validated using finite element analysis. The energy absorption capabilities and deformation behavior of the different microlattice structures are explored. The analysis also establishes better mechanical behavior of tetrahedral microlattice structures as compared to BCC microlattice.

Synchrotron Imaging of the Influence of Oxidation with Powder Age on Cracking Phenomena during Laser Powder Bed Fusion of CM247: David Rees1; Chu Lun Alex Leung1; Gowtham Soundarapandiyan2; Sebastian Marussi1; Saurabh Shah1; Robert Atwood3; Ben Saunders4; Gavin Baxter4; Peter Lee1; 1University College London; 2Coventry University; 3Diamond Light Source Ltd.; 4Rolls-Royce plc.
    Laser powder bed fusion (LBPF) of Ni-based superalloys provides a cost-effective method for the production and repair of low volume components that operate in high-temperature and high-stress environments. Precipitation hardened alloys such as CM247 are highly susceptible to cracking either during processing (hot-, liquation-, and ductility-dip cracking) or during heat-treatment; however, the underlying phenomena behind events causing cracking remains unclear. Both the complex thermal history of LPBF and feedstock composition plays key roles in crack susceptibility. Here, we investigate the effect of different levels of powder oxidation on CM247 powder during LPBF to identify a suitable trade-off between build quality and economic value. To observe crack evolution, we performed high-speed synchrotron X-ray imaging of the LPBF of CM247 powders over a range of processing parameters. Our results inform the extent to which aged powder may be reused, recycled, or scrapped due to high oxygen content.