Additive Manufacturing: Materials Design and Alloy Development IV: Rapid Development: Poster Session
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS: Additive Manufacturing Committee, TMS: Integrated Computational Materials Engineering 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 1, 2022
Room: Exhibit Hall C
Location: Anaheim Convention Center


NOW ON-DEMAND ONLY - J-25: Can Hot Cracking in LPBF Steel be Mitigated by Controlling the Powder Recoating Speed?: Tan-Phuc Le1; Qingyang Lu1; Shubo Gao1; Jay Carroll2; Matteo Seita1; 1Nanyang Technological University; 2Sandia National Laboratories
    Stainless steel 316L is known for its low susceptibility to hot cracking during laser powder bed fusion (LPBF) processes. In this work, however, we observe a clear increase in hot cracking when using a fast powder recoating velocity of 250 mm/s, with a consequent decrease in the alloy ductility. To investigate the origin of this phenomenon, we carry out a series of LPBF experiments using identical process parameters but different recoating velocities. We analyze both the powder layer using our proprietary technology as well as the microstructure of the solid samples produced using standard characterization techniques. Our results show that there are two dominant factors contributing to hot cracking—namely the powder layer thickness and the thermal buildup—both of which depend on the powder recoating velocity. This work may be useful for maximizing printing efficiency by decreasing part production time without exacerbating part performance.

NOW ON-DEMAND ONLY - J-26: Deformation Behavior of Powder Bed Fusion Additive Manufactured Ti6Al4V Alloy at High Temperatures: Md Jamal Mian1; Jafar Razmi1; Leila Ladani1; 1Arizona State University
    Powder bed fusion additive manufacturing (PBF-AM), an efficient technique to fabricate complicated geometries with different metals, is extensively used for shaping Ti6Al4V alloy. Due to having various crucial applications, the high temperature deformation behavior of Ti6Al4V is of interest particularly to aircraft engine manufacturers. Multiple factors influence the high temperature mechanical behavior of this material including the evolution of grain orientation, texture, dislocations and inherent defects. This study analyzes the effect of these microstructural features on mechanical behavior of PBF-AM built Ti6Al4V at various temperatures up to 600°C. Electron back scattered diffraction analysis is conducted on samples before and after the tensile test to determine possible softening mechanisms, microstructural changes and anisotropic behaviors as a function of temperature. Moreover, 3D X-ray CT analysis is conducted to examine the internal defects which varies between 0.05–0.17% depending on the build orientation and their impact on the observed behaviors of the samples.

J-27: Design and Analysis of Metal Based Brake Caliper Using FEA and Simufact for Its Development Using Additive Manufacturing: Swapnil Kumar1; Sundar Atre1; 1University of Louisville
    The braking system stops the vehicle from moving and to stop a vehicle, brake torque needs to be delivered from the brake caliper to the disc brake which stops the rotating wheels, and torque produced by the brake caliper needs to be greater than the torque produced at the wheels. Appropriate vehicle design parameters need to be formulated to ensure optimum design parameters for the brake caliper and optimum torque at the wheels. Design and manufacturing analysis have been carried out for metal additive manufacturing based brake caliper. For design modeling, SolidWorks has been used and from the simulation aspect, Ansys and Simufact have been used to analyze the stress, displacement, and surface deviation. Force and torque calculations have been carried out for the brake caliper using MATLAB. The designed brake caliper is optimum in terms of weight, cost, and efficiency. 90% brake efficiency has been achieved.

J-28: Effect of Hot Isostatic Pressing on the Microstructure of Directionally Solidified Nickel Alloy after SLM: Evgenii Borisov1; Anna Gracheva1; Vera Popovich2; Anatoly Popovich1; 1SPbPU; 2TU Delft
    The paper investigates the effect of hot isostatic pressing of single-crystal nickel-based alloy manufactured by selective laser melting (SLM) with a high-temperature substrate preheating. A study of the structure and phase composition of the material before and after treatment has been carried out. It was found that as a result of such treatment, the ratio and proportion of the strengthening phases changes, however, due to slow cooling after treatment, the optimal ratio and shape of the inclusions is not fixed. In addition, the hardening particles are precipitated.

J-29: Effect of Porosity and Composition on Mechanical and Biological Properties of Additively Manufactured Titanium Alloy: Sushant Ciliveri1; Indranath Mitra1; Susmita Bose1; Amit Bandyopadhyay1; 1Washington State University
    Porosity on metal implants has been proven to enhance osseointegration in orthopedic applications in vivo. Additive manufacturing (AM) offers the freedom of designing desired pore morphology to achieve the required porosity on implant material in a single operation. The strength of such designed porous structures depends on overall volume fraction porosity, pore-morphology, pore size, and pore-pore connectivity. Since implants are under constant loading conditions in vivo, it is essential to evaluate the strength of porous metals under compressive and shear loading. Ti6Al4V is the most widely used material for load-bearing orthopedic implants. Although CpTi has higher biocompatibility than Ti6Al4V, it shows lower strength than the latter. Our work focuses on evaluating the effect of reduced Al and V contents in Ti6Al4V towards mechanical and biological performance compared to that shown by Ti6Al4V and CpTi, respectively.

J-31: Geometric Effects on Microcracking in Superalloys Produced by Laser Powder Bed Fusion: Marcus Lam1; 1Monash University
    Microcracking has been challenging for superalloys printing by laser powder bed fusion (LPBF) and studied for years. While several underlying causes had been reported, most of the research only experimented on samples with simple shapes far from the complex-shaped components such as turbine blades or heat exchangers. Indeed, cracking is reported from the industry on components with ‘optimized’ processes, even though not observed previously in samples. In this presentation, the influence of the sample geometry on crack susceptibility will be revealed and discussed. Our research indicates that the mid-planes of rectangular samples often used in the literature are only the best-case scenario for microcracking. Therefore, it could be misleading if the results are used to verify the crack-free state of the process or alloys. We investigated the cause of the crack susceptibility difference from the geometric effects by microscopy analyses and process simulation.

J-32: Investigation of Solidification Kinetics and Its Effect on Mechanical Response of IN718 Fabricated via Selective Laser Melting: Digvijay Parganiha1; Priyanka Agrawal1; Ravi Sankar Haridas1; Rajiv S. Mishra1; Hirotsugu Kawanaka2; Shinji Matsushita2; Yusuke Yasuda2; Seung Hwan C. Park2; Wei Yuan3; 1University of North Texas, Denton; 2Research & Development Group, Hitachi Ltd, Japan; 3Research & Development Division, Hitachi America Ltd.
    The microstructural evolution in the selective laser melting processed IN718 alloy was evaluated and linked with the mechanical response during monotonic and cyclic deformation. The microstructural features studied included texture, grain size and morphology, type of precipitates and volume fraction, elemental partitioning, and defects. The investigation was carried out in different sample orientations with respect to the built direction to study the anisotropy. The thermal gradient at different locations along the built direction was related to the macrotexture to understand the microstructural evolution. This aided in understanding the solidification kinetics and correlating it to the solidification map of IN718 (a plot of the thermal gradient, G, vs. the growth rate, R.)

J-33: Mechanism of Oxygen-induced Hot Cracking of IN738 during Additive Manufacturing: Kenhee Ryou1; Boryung Yoo1; Pyuck-Pa Choi1; 1Korea Advanced Institute of Science and Technology
    Even though IN738 alloy shows notable strength and oxidation resistance behavior in high-temperature among the Ni-based superalloy, hot-cracking behavior resulting from poor weldability is the detrimental factor on the application of additive manufacturing. Usually, a γ-γ' eutectic microstructure with low melting temperature is pointed out as a cause of hot-cracking in the case of Ni-based superalloys. However, we report on a novel hot-cracking mechanism in a direct laser deposited IN738, using joint electron, X-ray, and atom microscopy. The majority of the observed cracks were related to oxides formed in grain interiors and boundaries. Using atom probe tomography, we detected an intermediate zone between oxides and the base alloy, where oxygen existed in solid solution and chemical compositions varied due to the oxide formation. The variation in composition lowered the melting point of the matrix while the oxides promoted stress concentration and crack nucleation, thus causing liquation cracking during reheating.

J-36: Tailoring the Preferred Texture of SS316L & IN718 in Laser Bed Powder Fusion: Prosenjit Biswas1; Ji Ma1; 1University of Virginia
    Stainless-Steel 316L (SS316L) and Inconel 718 (IN718) both are FCC alloys having the same preferred solidification orientation along the cellular solidification structures that form during rapid solidification. Despite these, their reported texture along build direction generally differs: SS316L develops <110> while IN718 develops <100>. We study the thermal history and solidification microstructure development in laser bed powder fusion through systematic experimentation supported by finite element thermal modeling. These FCC alloy systems were directly compared under various processing and solidification to determine the fundamental differences and similarities in cellular solidification. We further showed how the growth of cellular structures can be controlled to tailor the preferred texture along the build direction of SS316L & IN718 as a function of process parameters.

J-37: The Development of a Directed Energy Deposition (DED) Printability Framework for Improving Part Density and Performance in a 316L Stainless Steel: Matthew Vaughan1; Michael Elverud1; Jiahui Ye1; Peter Marcos1; Raiyan Seede1; Sean Gibbons2; Raymundo Arroyave1; Alaa Elwany1; Ibrahim Karaman1; 1Texas A&M University; 2Air Force Research Laboratory
    Recently, research efforts of novel steel alloys, where high strength and toughness are critical features, have significantly expanded. A proven method to achieve high performance is via the Hall-Petch effect. While the additive manufacturing (AM) directed energy deposition (DED) technology provides a novel and effective way for producing significant grain refinement (by imposing a rapid cooling rate upon solidification), its inherent complexity merits a need for the development of a systematic DED framework that quickly identifies the ideal printability space for a given steel, and subsequently enables one to print the material to full density and dimensional accuracy. Afterwards, achieving optimal strengthening in novel high strength steels via DED and the Hall-Petch effect would be much more straightforward. To meet this need, the present study proposes a DED printability framework using 316L stainless steel, following an approach that is easily adaptable to other high-end steel alloys.