Advances in Titanium Technology: Invited Talks
Sponsored by: TMS Structural Materials Division, TMS: Titanium Committee
Program Organizers: Yufeng Zheng, University of North Texas; Zachary Kloenne, Ohio State University; Fan Sun, Cnrs Umr 8247 - Chimie Paristech Psl; Stoichko Antonov, National Energy Technology Laboratory; Rongpei Shi, Harbin Institute of Technology
Monday 2:00 PM
February 28, 2022
Room: 252A
Location: Anaheim Convention Center
Session Chair: Yufeng Zheng, University of Nevada Reno
2:00 PM Invited
Developing New Metastable Beta-titanium Alloys and Optimizing Their Properties through Heat-treatments: Brian Welk1; Nevin Taylor1; Mathew Cohen1; Zachary Kloenne1; Hamish Fraser1; 1Ohio State University
Metastable beta-titanium alloys have exhibited attractive balances of properties for structural components. In this paper, the results of research aimed at developing new metastable beta-titanium alloys are presented, and the degree to which their properties may be optimized by heat-treatment is described. Regarding the development of new alloys, two methods have been employed. The first is based on the characterization of microstructure in existing alpha/beta alloys, and the second involves dilute alloying additions to existing alpha/beta alloys. Regarding the optimization of microstructure, structural and compositional instabilities have been exploited in order to produce refined microstructures using heat-treatments that do not make use of rapid quenching from a temperature above the beta transus. Hence, these heat-treated samples exhibit refined uniform microstructures and do not possess significant residual stresses. These uniform microstructures have been produced in large scale samples to demonstrate the degree of deep hardening that can be developed.
2:20 PM Invited
Defect Engineering for Heterogeneous and Adaptive Microstructures: Yunzhi Wang1; 1Ohio State University
This presentation demonstrates how to create various heterogeneous and adaptive microstructures by defect engineering for controlled strain release during elastic and plastic deformations. Compositional and/or structural non-uniformities engineered through various non-conventional phase transformation pathways, thermomechanical processes, and novel processing methods such as 3D-printing are shown to have the ability to activate different elastic and plastic deformation mechanisms (including intrinsic elasticity and pseudo-elasticity, and dislocation plasticity and transformation plasticity) at different stages of deformation, offering well-controlled strain release and exceptional mechanical properties including linear superelasticity, ultralow elastic modulus, and an excellent combination of strength, ductility and work-hardening ability. Structural heterogeneities created during deformation could be coupled with localized phase transformations that act as a self-healing mechanism, offering an outstanding creep resistance.
2:40 PM Invited
Tuning Elastic Properties of ω-phase to Engineer High Strength-ductility β-Titanium Alloys: Riyadh Salloom1; Srinivas Aditya Mantri1; Mohan Sai Kiran Nartu1; Abhishek Sharma1; Sriswaroop Dasari1; Ravisankar Haridas1; Srinivasan Srivilliputhur1; Rajarshi Banerjee1; 1University of North Texas
Recent reports suggest short term aging (~1-10 mins) of β-Titanium alloys at sub-ω solvus temperatures, severely affects their mechanical properties which may lead to an almost two-fold increase in yield-strength with a concurrent reduction in tensile ductility to ~0%. While the conventional wisdom attributes this to the brittleness of ω-phase, using experiments coupled with DFT studies in binary β-Titanium alloys we show that the elastic properties of the ω-phase can be systematically varied as a function of its composition to enhance both the ductility and strength of the Ti-alloy. Further, the efficacy of this microstructural design approach has been explored over a wide range of strain rates (10-3 sec-1 to 103 sec-1) in the case of a model binary alloy (Ti-20V at.%) as well as a commercial alloy (Ti-10V-2Fe-3Al wt.%). Coupling with a detailed investigation of the associated deformation-mechanisms we provide insights for a wider application of such an approach.
3:00 PM Invited
NOW ON-DEMAND ONLY - Enlarging the Palette of Mechanical Properties of TI64 by a Quenching and Partitioning Approach: Stephane Godet1; Loic Malet1; Frederic Prima2; Odeline Dumas1; 1Universite Libre De Bruxelles; 2Chimie ParisTech
The usual bimodal microstructure of wrought TI64 is known to provide an excellent yield strength to density ratio. However, its poor work-hardening capacities brings about limited ductility. Moreover, the post-uniform elongation is also very limited. In the present work, we report the beneficial influence of dual-phase microstructures obtained by quenching from the alpha+beta phase field. Under certain circumstances, such dual-phase microstructure exhibit martensite reorientation induced plasticity, that was never reported in this well-known industrial alloy. The dual-phase microstructures are further annealed allowing the partitioning of V from the supersaturated martensite. Depending on the initial dual-phase microstructure and the parameters of the annealing treatments, a very large palette of mechanical properties is obtained. The strength levels, work-hardening behaviors, ductilities and post-uniform elongations are discussed.
3:20 PM Invited
Microstructure Formation in Titanium Alloys: Abigail Ackerman1; Benjamin Savitzky2; Colin Ophus2; Mohsen Danaie3; Phani Karamched4; David Dye1; 1Imperial College, London; 2National Center for Electron Microscopy Lawrence Berkeley National Laboratory; 3Electron Physical Sciences Imaging Centre (ePSIC), Diamond Light Source; 4University of Oxford
Titanium alloys often have complex microstructures that form due to intricate thermomechanical processing. By understanding the fundamental microstructural formation mechanisms, changes to the processing can be applied to create an advantageous microstructure. Ti 6246 (6Al-2Sn-4Zr-6Mo wt%) is a titanium alloy that is used in the intermediate pressure compressor of jet engines, in a condition with basketweave µm-scale primary hcp α-Ti laths in a matrix of bcc β-Ti reinforced by smaller secondary α. Lengthscale strengthening by the secondary α is believed to be the main source of strength in the alloy, providing a barrier against slip band formation, which can be deleterious for the fatigue performance. Here, we use kinetic and interface modelling to understand the microstructural formation, and apply changes to the processing route to encourage defect assisted nucleation. Mechanical testing shows a stronger more fatigue resistant alloy, with advanced microscopy providing a fundamental explanation for the improved properties.