Processing—Microstructure—Property Relationships of Titanium and Titanium Alloys: Session I
Sponsored by: TMS Titanium Committee
Program Organizers: Yufeng Zheng, University of North Texas; Rongpei Shi, Harbin Institute of Technology; Michael Gram, Pratt & Whitney
Wednesday 8:00 AM
October 20, 2021
Room: B246
Location: Greater Columbus Convention Center
Session Chair: Yufeng Zheng, University of Nevada Reno; Rongpei Shi, Lawrence Livermore National Laboratory
8:00 AM Invited
Exploiting Structural and Compositional Instabilities in Titanium Alloys to Optimize Microstructure/Property Interrelationships in Samples Fabricated by Additive Manufacuring: Brian Welk1; Nevin Taylor1; Zachary Kloenne1; Yufeng Zheng2; Rajarshi Banerjee3; Hamish Fraser1; 1The Ohio State University; 2University of Nevada-Reno; 3University of North Texas
Regarding additive manufacturing (AM) of titanium alloys there are two problems to be solved, the first involving the need to effect an equaixed microstructure in printed parts, rather than the coarse columnar microstructure that is usually observed, and the second is the optimization of microstructure by post-processing heat-treatments. Using the alloy Ti-6Al-4V, the first of these problems has been solved by use of dilute alloying, added to increase the freezing range and so the probability of solutal undercooling during the rapid solidification experienced in AM. Interestingly, the addition of 3%Fe to Ti-64 changes the nature of the alloy from an alpha/beta alloy to a metastable beta Ti alloy. This allows for heat-treatments that are different from those applied to Ti-64, and involve exploitation of structural and compositional instabilities to produce refined microstructures uisng heat-treatments that do not make use of rapid quenching from a temperature above the beta transus. Hence, these heat-treated samples exhibit refined microstructures and do not possess significant residual stresses. Preliminary assessments of mechanical properties will be presented.
8:30 AM Invited
Regulating Elastic and Plastic Deformation by Heterogeneous Microstructure Design in Ti-alloys: Yunzhi Wang1; 1Ohio State University
In this presentation, I will give an overview on how to create various heterogeneous and adaptive microstructures by defect engineering for controlled strain release during elastic and plastic deformations of Ti-alloys. Compositional and/or structural non-uniformities engineered through various non-conventional phase transformation pathways, thermomechanical processes, and novel processing method 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, Invar and Elinvar anomalies, an exceptional combination of strength and ductility and work-hardening ability.
9:00 AM Invited
Influence of Athermal vs. Isothermal Omega Precipitation and Alpha Precipitation on TRIP/TWIP Deformation Mechanisms in Metastable Beta Ti alloys (invited): Srinivas Aditya Mantri1; Abhishek Sharma1; Riyadh Salloom1; MSKKY Nartu1; Sriswaroop Dasari1; Srinivasan Srivilliputhur1; Rajarshi Banerjee1; 1University of North Texas
This talk will focus on the effects of heat treatment on the phase transformations, mechanical properties, and deformation behavior in a commercially metastable Beta-Ti alloy, Ti-10V-2Fe-3Al(wt%) and a binary model alloy, Ti-20V(wt%), both exhibiting TRIP/TWIP effects in the single beta solid solution phase. Low temperature annealing resulting in formation/growth of omega precipitates, followed by subsequent annealing at higher temperatures, resulted in fine-scale alpha precipitation. A difference in the tensile properties and deformation mechanism was also noted between samples with a beta + omega microstructure versus those with a beta + alpha microstructure. While the single beta + athermal omega condition showed transformation induced plasticity (TRIP), leading to substantial strain-hardening, the beta + isothermal omega and beta + alpha condition deformed via slip. These results can be rationalize based on both the beta matrix stability coupled with the changes in the modulus of the omega precipitates.
9:30 AM
Nano-scale O” Phase and Fine-scale Alpha Precipitation in a Metastable Beta Ti-5Al-5Mo-5V-3Cr Alloy: Dian Li1; Stoichko Antonov2; Rongpei Shi3; Zachary Kloenne4; Hamish Fraser4; Yufeng Zheng5; 1University of Nevada-Reno; 2Max-Planck-Institut für Eisenforschung GmbH; 3Lawrence Livermore National Laboratory; 4Ohio State University; 5University of Nevada-Reno
The microstructures in metastable beta titanium alloys mainly contain the hcp alpha precipitates and the bcc beta matrix, generated by the precipitation reaction during the aging treatment. In general, alpha precipitates prefer to nucleate along the beta grain boundary and form a thick layer of grain boundary alpha microstructure. However, by introducing nano-scale particles into the interior of beta grains, fine-scale intragranular alpha microstructures can be produced in the metastable beta titanium alloys. In this work, the characterization of nano-scale ordered O” phase and the influence of nano-scale O” phase on subsequent alpha precipitation in a metastable beta Ti-5Al-5Mo-5V-3Cr alloy will be introduced. The structure and composition of O” particles was investigated using aberration-corrected S/TEM and atom probe tomography. The driving force from these O” phase particles for the subsequent alpha precipitation was studied using CALPHAD. The fine-scale intragranular alpha microstructure produced will be discussed in detail.
9:50 AM
A Data-driven Analysis for Selection and Use of Conventional Ti Alloys for Aeroengine Applications and Future Directions: Tanjore Jayaraman1; Ramachandra Canumalla2; 1University of Michigan-Dearborn; 2Weldaloy Specialty Forgings
Conventional high-temperature titanium alloys (near-α alloys) find themselves in advanced aeroengines for applications due to their superior combination of ambient and elevated-temperature mechanical properties and oxidation resistance. The inherent mechanical properties are known to be sensitive to chemical composition, thermomechanical processing, and microstructural constituents. We adopted a data-driven approach to analyze a plethora of alloys, viz. IMI829, IMI 834, Ti-1100, etc. reported in the literature to date. We applied a novel methodology combining advanced statistical analysis: cluster analysis (CA) and principal component analysis (PCA), and multiple-attribute decision making (MADM) to unearth the voice of the data. The investigation compares several grades/variants of the alloys, suggests potential substitutes for the existing alloys, and provides directions for improvement and/or development of titanium alloys over the current ones for use at higher temperatures and thus help push out some of the heavier alloys and consequently help in reducing the weight of the engine.
10:10 AM Break
10:30 AM
The BMG to Ti Weld, a Pool for Microstructure: Property Characterization: Dan Sorensen1; Eric Hintsala2; Jesse Pischlar3; Joseph Stevick4; Bernie Li3; Daniel Kiener5; Jason Meyers6; Antonio Ramirez7; Douglas Stauffer2; Robert Ritchie8; 1Boston Scientific; 2Bruker Nano Surfaces & Metrology; 3Medtronic; 4Hummingbird Scientific; 5Montanuniversitat, Leoben; 6University of Minnesota; 7Ohio State University; 8University of California, Berkeley
The medical device industry places unique demands upon materials, such as high fatigue resistance and biocompatibility, grade 2 Titanium being a ubiquitous example. A promising new(er) material, Vitreloy 105 has several attractive properties including high strength, corrosion resistance, low density and near net shape molding. A variety of techniques were utilized to optimize the welding schedule, but the focus here is on an optimized weld pool that creates an opportunity to explore non-equilibrium, titanium containing, microstructures. Using micro-cantilever experiments in a mapped weld pools. Zirconium particle rich regions toughen the cantilevers, when compared to bulk Vitreloy 105. These same regions exhibit extremely high strengths.
10:50 AM
Role of Novel Highly-indexed Twinning in Hierarchical α Microstructure in 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 für Eisenforschung GmbH
The mechanical properties of metastable β titanium alloys are highly dependent on the size, morphology, number density and distribution of α phase precipitates formed during different thermomechanical processings. Recent studies have shown that the α microstructure can be tuned via various pre-formed nanoscale metastable particles and interfaces in the metastable β titanium alloys. In this work, the role of highly-indexed twinning in the hierarchical α microstructure in a metastable β Ti-5Al-5Mo-5V-3Cr (wt%, Ti-5553) alloy has been investigated using scanning electron microscopy and transmission electron microscopy. A novel {10 9 3}<3 3 1>β highly-indexed twin type was generated in Ti-5553 via cold-rolling and a hierarchical α microstructure composed of coarse α layers, α sub-layers and fine-scale α precipitates was formed via accurately controlled heat treatment. The microstructure evolution pathway to form α precipitates of different size scales will be discussed in detail.
11:10 AM
The Composition-processing-microstructure-property Relationships of Fe and Al Modified Ti-Cr Alloys: Joann Ballor1; Jonathan Poplawsky2; Elizabeth Kautz3; Bharat Gwalani3; Arun Devaraj3; Masahiko Ikeda4; Carl Boehlert1; 1Michigan State University; 2Oak Ridge National Laboratory; 3Pacific Northwest National Laboratory; 4Kansai University
Low-cost beta-Ti alloys are potential replacements for heavier alloys currently used in high-strength applications. The low-cost beta-titanium alloys Ti-11Cr-xFe-xAl(at%), (0≤x≤5.3) were subjected to a 400C aging treatment under vacuum for varying times up to 12 hours to induce the beta-to-omega and/or the omega-to-alpha phase transformations. A multi-modal approach was used to obtain a comprehensive understanding of the composition-processing-microstructure-property relationships. Microstructure changes with respect to Fe and Al contents and aging times were investigated using scanning electron microscopy and transmission electron microscopy, and the omega and alpha phases were identified. Atom probe tomography reveals diffusion during the phase transformations. The alloy’s mechanical properties were investigated using tensile and hardness testing. The Ti-11Cr alloy exhibited a large increase in hardness after 0.75 hours of aging. All alloys exhibited maximum hardness after 12 hours of aging. APT was conducted at ORNL's CNMS, which is a U.S. DOE Office of Science User Facility.