Advances in Titanium Technology: General Topics in Ti Alloys
Sponsored by: TMS Structural Materials Division, TMS: Titanium Committee
Program Organizers: Yufeng Zheng, University of Nevada-Reno; Zachary Kloenne, Ohio State University; Fan Sun, CNRS - PSL Research University; Stoichko Antonov, National Energy Technology Laboratory; Rongpei Shi, Lawrence Livermore National Laboratory

Thursday 8:30 AM
March 3, 2022
Room: 252A
Location: Anaheim Convention Center

8:30 AM  
Hierarchical α Microstructure in a Metastable β Ti-5Al-5Mo-5V-3Cr Alloy: Dian Li1; Wenrui Zhao1; Xing Zhang2; Stoichko Antonov3; Yiliang Liao2; Yufeng Zheng1; 1University of Nevada, Reno; 2Iowa State University; 3Max-Planck-Institut fr Eisenforschung GmbH
    In the metastable β titanium alloys, α precipitates displaying different morphologies, size scales, and distribution can be achieved from various phase transformation pathways under different thermomechanical treatments. For example, it has been reported that fine-scale α microstructure can be tailored via the assistance of pre-formed metastable nanoscale ω phase during slowly continuous aging. In this work, a hierarchical α microstructure composed of coarse α layers, α sub-layers and fine-scale α plates in a metastable β Ti-5Al-5Mo-5V-3Cr (wt%, Ti-5553) alloy has been studied using scanning electron microscopy and transmission electron microscopy. The number density and morphology of the different α precipitates were quantitatively analyzed using MIPAR image processing software. High-index {10 9 3}<3 3 1>β twin and its substructure were characterized in detail. The role of these high-index twins in the formation of hierarchical α microstructure will be introduced.

8:50 AM  
The Influence of Fe and Al on the Microstructure and Mechanical Performance of Ti-Cr Alloys: Joann Ballor1; Jonathan Poplawsky2; Elizabeth Kautz3; Bharat Gwalani3; Arun Devaraj3; Alexandra Zevalkink1; Scott Misture4; Masahiko Ikeda5; Carl Boehlert1; 1Michigan State University; 2Oak Ridge National Laboratory; 3Pacific Northwest National Laboratory; 4Alfred University; 5Kansai University
    The low-cost alloying elements Fe and Al were added to a base Ti-13Cr(wt.%) alloy, and a multi-modal investigation was conducted to determine their effects on the microstructure and mechanical performance after subjecting the alloys to 400C heat treatments. Transmission Electron Microscopy and in-situ X-ray Diffraction, performed at 400C, revealed the evolution of the phases and the resulting microstructures. The beta phase transformed to the omega and alpha phases in the Ti-13Cr alloy, while the 1Fe(wt.%) and 3Al(wt.%) additions tended to suppress the formation of the omega phase but not the alpha phase. Atom probe tomography indicated elemental segregation during the phase transformations, suggesting diffusional pathways. Room temperature tensile tests revealed exceptional strengthening after the 400C treatment, and the Ti-13Cr-1Fe-3Al(wt.%) alloy exhibited the best balance of strength and ductility. 400C in-situ Resonant Ultrasound Spectroscopy measurements revealed the evolution of the elastic modulus, consistent with the phase transformations.

9:10 AM  
A Comparative Study on Mechanical Properties of Additively Manufactured Titanium Alloys: Mohammad Yasin1; Arash Soltani-Tehrani; Meysam Haghshenas2; Shuai Shao1; Nima Shamsaei1; 1Auburn University; 2University of Toledo
    Titanium alloys, due to their high strength to weight ratio, proper corrosion resistance and biocompatibility, have been extensively used in aerospace, automotive and medical applications. On the other hand, certain properties, such as high chemical reactivity, high hardness and low thermal conductivity, make them challenging to machine. Therefore, additive manufacturing (AM) processes have gained a lot of attention to produce near-net shape parts from a wide range of titanium alloys. While a lot of studies can be found in the literature for Ti-6Al-4V, knowledge on other titanium alloys in the AM form is still lacking. In this study, the microstructure, as well as tensile and fatigue behavior of three additively manufactured titanium alloys, namely Ti-5Al-5V-5Mo-3Cr, Ti-5Al-5Mo-5V-1Cr-1Fe and Ti-6Al-2Sn-4Zr-2Mo-0.08Si have been evaluated in comparison to the well-studied Ti-6Al-4V. All specimens were fabricated using an EOS M290 laser beam powder bed fusion AM machine.

9:30 AM  
Development of a Phenomenological Equation to Predict Yield Strength in Additively Manufactured Ti-5Al-5V-5Mo-3Cr: Andrew Temple1; Madison Harrington1; Peter Collins1; 1Iowa State University
    The microstructure and resulting mechanical properties of additively manufactured metastable beta titanium alloys like Ti-5Al-5V-5Mo-3Cr are highly tunable through post-deposition heat-treatment. The size, distribution, and morphology of the microstructural features varies greatly with heat-treatment, requiring the meticulous development of methods for the characterization and quantification of the heat-treated microstructures. During heat-treatment the as-deposited samples were heated to temperatures (700-785C) below the beta transus and held at sub-transus temperatures for four hours before cooling at varying rates (5-500C/min) to room temperature. The samples were then aged for six hours at temperatures ranging from 500-650C. The yield and tensile strengths of the heat-treated samples were measured in uniaxial tension, with yield strengths ranging from 924-1535 MPa for 28 unique heat-treatment conditions. The application of a new phenomenological equation for the prediction of yield strength will be presented to further elucidate the microstructure-property relationships of heat-treated Ti-5553 produced by laser powder bed fusion.

9:50 AM  
Microstructural and Mechanical Properties Structural Repairs of near α and near Titanium Alloys by Additive Friction Stir Deposition: Christopher Williamson1; Zack Tew1; Malcolm Williamson1; James Jordon1; Paul Allison1; 1The University of Alabama
    In this work, Additive Friction Stir Deposition (AFSD) process was investigated to deposit and repair structural titanium alloys, namely the near α alloy Ti-6Al-4V and the near alloy Ti-6Al-2Sn-4Zr-6Mo. Acceptable processing windows were developed for both alloys that allowed for fully dense depositions as well as creating a fully bonded repair in simulated damaged substrate grooves. Subsequent microstructural analysis was completed to evaluate the effects of the varying process parameters on the titanium microstructure in comparison to previous studies of AFSD of Ti64 to capture changes in the grain size, texture, and hardness from the wrought material. Following the selection of a parameter set for each alloy, the mechanical properties of repaired specimens were compared to wrought plate specimens and subsequent post-mortem fractography to elucidate changes in the failure mechanism and to prove the capability of AFSD repair for in-field use.