A dataset for the development, verification, and validation of microstructure-sensitive process models for near-alpha titanium alloys

Abstract

Near-alpha titanium alloys are used for moderate-temperature applications in the early stages of the compressor in gas turbine engines. The quasi-static and fatigue properties of these alloys depend heavily on microstructure due to the absence of hard second phases and inclusions which can nucleate voids or cracks. Moreover, these alloys are known to exhibit a significant reduction in fatigue life when subjected to high mean stress or upon the application of dwell-fatigue cycles. Previous analysis has elucidated the microstructural features that drive these properties; the most important features are the volume fraction, size, and shape of clusters of similarly oriented alpha particles or microtextured regions (MTRs). To date, there have been few efforts to elucidate in a quantitative fashion the evolution of MTRs during thermomechanical processing (TMP). To meet this need, we have performed hot-compression tests on Ti-6Al-2Sn-4Zr-2Mo-0.1Si billet material with high-aspect-ratio MTRs at 0°, 45°, and 90°to the direction of primary metal flow during manufacture (i.e., the billet axis), thoroughly characterized the initial and final microstructures, and quantified field variables via finite-element method (FEM) process simulations for each experiment. These data can be used for a variety of purposes including the development, verification, and validation of models for microstructure/texture/microtexture evolution and defect formation.

A Hierarchical Multiscale Modeling Investigation on the Behavior of Microtextured Regions in Ti-6242 α/β Processing

“…RD, ND, and TD (transverse direction) were determined such that the ND pole figures coincided with the experimental measurement [17,18]. Note that both the compression direction and MTR orientation were changed in the mesoscale simulations, such that the uniaxial compression boundary condition can be conveniently applied, and the angle between the MTR axis and compression axis is the same as in the high temperature compression experiment [13,15]. For the mesoscale simulations shown in Figure 2, each MTR is approximated using idealized geometry and pure initial orientation.…”

“…Then, a hierarchical multiscale modeling framework is introduced, where models of clustered α p particles with representative microtexture are subjected to various strain histories from 1172 K mesoscale simulations. Lastly, the high-temperature compression experiment [13] is briefly summarized, which motivates the current investigation.…”

“…The units ofg (j) , h 0 are MPa; the other parameters are unitless. The transversely isotropic elastic constants were adjusted from the room temperature values in [16] to match the bulk stress-strain curve at higher temperature [13] while maintaining their relative ratio.…”

“…The average MTR size and α p particle size were also taken from the EBSD measurement [15], and grain shapes were generated based on a grain growth simulation. The average MTR diameter of the 209 mm diameter samples used in the high-temperature compression experiment [13] was 196 µm in the radial direction, while the average α p particle diameter was 10 µm in the radial direction [15]. In the mesoscale model, the MTR diameter is 300 µm, while the finite element edge length is 1.7 µm.…”

“…This paper extends the previous work by considering the distributed nature of α p particles within MTRs to more precisely capture the morphology evolution of MTRs under different strain paths. Specifically, the initial orientation distribution and particle size distribution of α p particles were extracted from the billet material [13]. These distributions were further employed to generate a statistically equivalent representative volume element (RVE) for the microscale problem of a hierarchical multiscale modeling framework.…”