Advances in Titanium Technology: Session VII
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 (Shenzhen)
Thursday 8:30 AM
March 23, 2023
Room: Cobalt 500
Location: Hilton
Session Chair: Zhi Liang, QuesTek Innovations LLC
8:30 AM Invited
A Holistic Approach to Low-cost Ti: Zhigang Fang1; 1University of Utah
The prohibitive cost of titanium has challenged the Ti industry and has been a major focus of the research community globally for several decades. Although the powder metallurgy (PM) of Ti has shown promise to be a low-cost approach, it has not gained significant market acceptance because the performance-to-cost ratios of PM Ti cannot compete with that of the wrought alloys. To compete, the cost of Ti and Ti alloy powders must be drastically reduced, and the mechanical properties of sintered Ti alloys must be drastically improved. This presentation introduces both a low-cost powder production process and a sintering technology that can produce Ti-6Al-4V with wrought-like microstructure and mechanical properties.
9:00 AM Invited
Combined Modeling-Experimental Approach for Investigating Hydrogenation of Titanium: Tae Wook Heo1; 1Lawrence Livermore National Laboratory
Understanding thermodynamic and kinetic behavior of hydrogen in Ti is key for preventing and improving corrosive and functional roles, respectively, of hydrogen for structural and energy storage applications. However, knowledge gaps remain due to the complexity of the associated mechanisms incorporating multiscale/multiphysics nature. Specifically, these involve coupled interfacial phenomena, including surface reaction, mass transport, structural transformation, and phase evolution. Therefore, several experimental and modeling approaches are needed to explore various facets of titanium hydrogenation mechanisms. This presentation will report our recent progress in investigating hydrogenation behavior in Ti using the combined modeling-experimental approaches. Particularly, we will discuss how multiscale/multiphysics factors are integrated for describing hydrogen interactions in polycrystalline Ti. We will then show how experimental characterizations and modeling are combined to analyze hydrogen-Ti interactions, focusing on key chemical and physical phenomena: surface reaction selectivity, hydrogen transport through surface oxide and grain boundaries, hydride nucleation-and-growth, and thermal transport through metal-hydride microstructures.
9:30 AM Invited
Kinetically Induced Fine Secondary α-Ti phase Formation in a Novel As-cast Titanium Alloy: Zhi Liang1; Jiashi Miao2; Xuejun Huang2; Fan Zhang3; James Williams2; Alan Luo2; 1QuesTek Innovations LLC; 2The Ohio State University; 3National Institute of Standards and Technology
The formation of fine secondary hexagonal close packed (HCP) α-Ti precipitates provides major strengthening in a new cast titanium alloy. The phase transformation mechanisms from the body-centered cubic (BCC) β-Ti matrix to fine α phase in this new α-β titanium alloy were investigated experimentally and computationally using CALculation of PHAse Diagram (CALPHAD)-based thermodynamic and kinetic models. The discrete distribution of α precipitates was observed in the as-cast alloy with evidence of strong Fe partitioning. Two main size groups of α precipitates and the Fe partitioning were characterized using scanning electron microscopy, scanning transmission electron microscopy, and synchrotron-based small-angle X-ray scattering techniques. A hypothesis of Fe-partitioning driven α precipitate nucleation and growth was validated by precipitation simulation using TC-PRISMA with customized thermodynamic and kinetic descriptions. These results suggested a new titanium alloy design route involving high mobility elements and demonstrated the capability of CALPHAD-based modeling in titanium alloy design.
10:00 AM Break
10:20 AM
Development of a Digital Twin for Characterisation of Titanium Alloy Microstructural Features Employing In-Process Machining Data: Thomas Childerhouse1; Oliver Levano Blanch1; Pete Crawforth1; Martin Jackson1; 1The University of Sheffield
This work presents a newly developed approach that employs cutting force data acquired during machining operations to characterise microstructural features of a workpiece. This non-destructive evaluation (NDE) technique offers capabilities at providing information regarding a workpiece’s processing history and microstructural properties using cutting force data captured during standard machining operations with conventional tooling. In this study, the machining force fluctuation response has been correlated to microstructural features, such as grain size and crystallographic texture and has been validated using conventional characterisation methods. The experiments performed demonstrate the possibility of rapidly characterising large areas (and in some cases, entire components), which would not be possible using conventional methods. This NDE technique offers manufactures a powerful quality assurance tool. By analysis of data acquired during roughing stages, non-conformant material can be identified early in the manufacturing process, whilst data captured during finishing can provide microstructural information directly linked to the in-service component.
10:40 AM
Nanoindentation Properties Evolution of Titanium with Different Oxygen Contents: Damien Texier1; Quentin Sirvin1; Charles Romain1; Henry Proudhon2; Vladislav Yastrebov2; Samuel Forest2; Marc Legros3; 1CNRS - Institut Clément Ader; 2Centre des Matériaux, Mines ParisTech; 3CEMES - UPR CNRS 8011
Ti-based alloys are excellent candidates for intermediate temperature applications due to high specific mechanical properties. However, the high solubility of oxygen in Ti at such temperatures makes Ti-based alloys particularly prone to oxygen dissolution and embrittlement. The oxygen rich layer (ORL), generally thicker than the external oxide scale, can extend over micrometers to tens of micrometers. The ORL is highly detrimental for the mechanical integrity of thin components. Therefore, assessing the local mechanical behavior at the sub-grain level and at the sub-ORL level is important to better understand the heterogeneous and anisotropic mechanical response of Ti as a function of the grain orientation and the local oxygen content. Large and high resolution nanoindentation maps were conducted using continuous stiffness measurement techniques and the reduced moduli and hardness measurements were correlated to EBSD and chemical data. Conventional nanoindentation tests were performed to investigate pop-in events within the oxygen-rich layer.
11:00 AM
The Effect of Dilute Si/Nb Alloying on High-temperature Oxidation of Titanium: Thomas Valenza1; Emmanuelle Marquis1; 1University of Michigan
Because of their high specific strength and good corrosion resistance, pure titanium and titanium alloys are well suited to structural applications in corrosive environments. However, rapid oxidation at high temperatures limits their use to approximately 550 °C. Although dilute Si/Nb alloying is known to be particularly effective at increasing oxidation resistance, both in pure O2 and more so in N2-containing atmospheres, mechanisms remain disputed. We oxidized pure Ti, Ti-0.8 at.% Si, and Ti-2 at.% Nb at 800 °C in Ar-O2 and N2-O2 and characterized the local microstructures and compositions of the scale and underlying metal. Si/Nb alloying led to moderate reductions in scale thickness in Ar-O2, and, in N2-O2, further reductions in scale thickness and sustained reductions in oxygen dissolution in the metal, which may be associated with the combination of a compact scale and the presence of N in solid solution below the scale.
11:20 AM
Effect of Macrozone Placement on Cracking in Bimodal Ti-6Al-4V: Yan Gao1; Nigel Martin2; Jamie Moschini2; David Dye1; 1Imperial College; 2Rolls-Royce plc
Large Ti-64 forgings can exhibit a High Cycle Fatigue life debit compared to plate or bar at high lives (N=1E8) associated with dwell-like faceted subsurface initiation. Forgings can also exhibit greater mean stress sensitivity, especially in notched fatigue. Here we examine the effect of placing the notch root in hard/soft macrozone combinations found in EBSD under R=0.5 HCF conditions and the associated initiation features and dislocations observed on subsequent SEM and TEM examination.