Macroregion Size Measurements in Bimodal Titanium Forgings Using Two-Dimensional Autocorrelation Method

Toubal, Lotfi; Bocher, Philippe; Moreau, A.; Lévesque, Daniel

doi:10.1007/s11661-009-0128-3

Cited by 6 publications

(3 citation statements)

References 22 publications

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“…More specifically, macrotexture, or the preferred orientation of a polycrystalline aggregate, impacts both low-and high-cycle fatigue properties; however, it has been shown that the presence and degree of microtexture is of paramount importance with regard to dwell-fatigue susceptibility [4]. Microtextured regions (MTRs) are clusters of alpha particles that appear fully spheroidized ("recrystallized") under conventional imaging modes but are found to have similar orientation when the spatial distribution of the texture components is investigated using electron backscatter diffraction (EBSD) and, in some instances, with optical microscopy [5]. Figure 1 illustrates the hierarchical nature and complexity of alpha+beta-processed titanium microstructures whose features range in size from 10s of nanometers (e.g., coherent, ordered Ti 3 Al precipitates) to multiple millimeters (MTRs).…”

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

Pilchak

Shank²,

Tucker

et al. 2016

Integr Mater Manuf Innov

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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.

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confidence: 99%

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

Pilchak

Shank²,

Tucker

et al. 2016

Integr Mater Manuf Innov

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“…On the other hand, our work was impaired by the difficulty to measure these dimensions with some reliable reference method. In a previous paper, we showed how difficult it can be to measure these dimensions by optical, metallographic techniques [19]. A solution was found by calculating the 2-dimensional autocorrelation function of the texture-sensitive optical image obtained after macro etching.…”

Section: Ultrasonicsmentioning

confidence: 99%

Evaluation of macrozone dimensions by ultrasound and EBSD techniques

Moreau

Toubal

Bocher

et al. 2013

Materials Characterization

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“…However, some have also pointed out that dwell-fatigue properties can vary within a single forged part (Davies, 1997;Ress, 1995;Uta, 2009). Titanium alloys are known to have texture heterogeneities, i.e., regions much larger than the grain dimensions where the local orientation distribution of the grains differs from one region to the next (Germain et al, 2005;Jha et al, 2005;Le Biavant-Guerrier, 2000;Moreau et al, 2013;Toubal et al, 2009aToubal et al, , 2009bToubal et al, , 2010. These relatively large regions, sometimes of millimetric dimensions, present specific crystallographic orientations and play a significant role in the early dwellfatigue damage of titanium parts (Le Biavant-Guerrier, 2000;Uta et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Bimodal dwell-fatigue Weibull distribution of forged titanium IMI 834

Toubal

Bocher

Moreau

2014

International Journal of Damage Mechanics

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This study addresses cumulative damage and its evolution during the cold dwell fatigue of a neartitanium alloy. An experimental study was undertaken to examine the evolution of life, strain, strength and damage of 13 titanium IMI 834 samples cut from a single disk forging. The samples were tested in the same dwell-fatigue loading conditions. In the dwell phase, the load is maintained at 80% of ultimate tensile strength (824 MPa, 90% of yield strength) for 30 s. The secant Young's modulus and inelastic strain at minimum load were measured in order to document the evolution of the irreversible damage against the number of cycles for all specimens. Experimental observations show significant differences in dwell-fatigue life and damage behavior. This mechanical analysis and an analysis of the cumulative Weibull reliability distribution suggest a bimodal dwell-fatigue failure process. Some features of the mechanical behavior can be used to sort the samples according to each of the two failure modes and improve the reliability of the fatigue test campaign.

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Macroregion Size Measurements in Bimodal Titanium Forgings Using Two-Dimensional Autocorrelation Method

Cited by 6 publications

References 22 publications

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

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

Evaluation of macrozone dimensions by ultrasound and EBSD techniques

Bimodal dwell-fatigue Weibull distribution of forged titanium IMI 834

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