Adiabatic shear localization in α-titanium: experiments, modeling and microstructural evolution

Chichili, D.R.; Ramesh, K.T.; Hemker, Kevin J.

doi:10.1016/j.jmps.2004.02.013

Cited by 85 publications

(37 citation statements)

References 22 publications

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“…Since the estimated temperature during machining in this study is lower than the reported critical temperature of 773 K (500°C), the recystallization process was not fully driven. These results are similar to those reported for pure a-Ti in Kolsky bar tests, [20] where the use of recovery specimens allowed the postmortem characterization of the evolving shear band. Chichili et al showed an evolution of highly elongated narrow grains aligned along the shear direction.…”

Section: Discussionsupporting

confidence: 87%

“…Chichili et al showed an evolution of highly elongated narrow grains aligned along the shear direction. [20] Meyer et al [10] postulated that the rotational dynamic recrystallization mechanism best explained the grain refinement occurring inside ASBs. The starting random dislocation distribution evolves into elongated cells during the severe deformation.…”

Section: Discussionmentioning

confidence: 99%

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Microstructural Characterization of Ti-6Al-4V Metal Chips by Focused Ion Beam and Transmission Electron Microscopy

Schneider

Dong

Meyer

2011

Metall Mater Trans A

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During machining, the cutting surface of a metal is subjected to high strain rates and temperatures. Due to the small mass of the formed chip, the metal is rapidly quenched, preserving the as-machined microstructure. These extreme conditions are reported to be favorable to form nanograin or ultrafine-grain microstructures. However, detailed investigation of this region is problematic due to the size of the chips and the difficulty in preserving the cutting surface microstructure during traditional transmission electron microscopy (TEM) preparation. This study investigates the use of focused ion beam (FIB) specimen preparation to preserve and TEM to image the microstructure of the secondary deformation zone (SDZ) at the cutting surface in chips of Ti-6Al-4V formed during machining. Use of the FIB allowed precise extraction of a side or transverse view specimen, which preserved the cutting surface to reveal an inhomogeneous microstructure resulting from the nonuniform distribution of strain, strain rate, and temperature. Initial imaging of a conventional TEM foil prepared from the plan view of the cutting surface revealed microstructures ranging from heavily textured to regions of fine grains. Using FIB preparation of a transverse foil, a layered microstructure was observed revealing a variation of fine grains near the cutting surface, which transitioned to coarse grains toward the free surface. At the cutting surface, a 10-nm-thick recrystallized layer was observed capping a 20-nm-thick amorphous layer.

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Section: Discussionsupporting

confidence: 87%

Section: Discussionmentioning

confidence: 99%

Microstructural Characterization of Ti-6Al-4V Metal Chips by Focused Ion Beam and Transmission Electron Microscopy

Schneider

Dong

Meyer

2011

Metall Mater Trans A

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“…The majority of the work performed in the _ e ¼ 10 3 to 10 4 s À1 range concerned a-Ti. [16,28,29] The microstructural evolution following high-strain-rate deformation was found to be similar to that of other metals and alloys that are susceptible to shear band formation, namely the formation of dislocation cells, subgrains, and DRX. Altogether, all the characterized materials bear a common overall microstructural evolution.…”

Section: Introductionmentioning

confidence: 59%

“…As the fracture zone is approached (higher strains), the microstructure gets refined by increasing the misorientation angle, resulting in subgrains as observed in similar cases for other materials. [9,11,12,22,28,29] Furthermore, for interrupted tests at the core of the potential fracture plane, an area with a high density of dislocations or avalanched dislocation cells is observed. No microstructural features are distinguishable, even though the corresponding SADPs indicate recrystallization in the form of incomplete rings.…”

Section: Discussionmentioning

confidence: 97%

Microstructural Aspects of Adiabatic Shear Failure in Annealed Ti6Al4V

Landau

Venkert²,

Rittel

2009

Metall Mater Trans A

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This work reports a comprehensive examination of the microstructural evolution in Ti6Al4V subjected to high-strain-rate deformation. The sequence of microstructural rearrangements leading to adiabatic shear banding is presented. A detailed microstructural comparison between two types of specimens, one that failed by adiabatic shear and the other that was strained to half its failure strain, is carried out. The main observation is that for this material, the microstructure of the two types of specimens is qualitatively identical, indicating that from approximately half the failure strain until adiabatic shear failure, no additional micromechanism is observed to develop and operate. Overall, the microstructure undergoes a significant refinement with the increasing strain until the formation of dynamically recrystallized grains. It is therefore suggested that the evolution of the volume fraction of recrystallized grains should be characterized from its early onset until final failure by adiabatic shear banding.

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“…Figure 3 gives an example of an impact result with adiabatic shear bands in TiAl6V4. [4,5] Low cycle fatigue trials have shown the crack initiating potential of these anomalies.…”

mentioning

confidence: 99%

Electromagnetic Detection and Characterization of Tungsten Carbide Inclusions in Non‐Ferromagnetic Alloys

et al. 2005

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Manufacturing anomalies introduced during machining of critical parts, although rare in occurrence, have become a significant cause of gas turbine disk cracking events in the aero‐engine. One kind of these anomalies is inclusion of foreign material. Breakage of the machine tool cutting edge can lead to residual tool particles being impacted in the surface of the component. These particles may initiate fatigue crack growth significantly reducing fatigue life. The paper presents electromagnetic methods for their detection and characterization based on eddy currents and residual magnetic fields.

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Adiabatic shear localization in α-titanium: experiments, modeling and microstructural evolution

Cited by 85 publications

References 22 publications

Microstructural Characterization of Ti-6Al-4V Metal Chips by Focused Ion Beam and Transmission Electron Microscopy

Microstructural Characterization of Ti-6Al-4V Metal Chips by Focused Ion Beam and Transmission Electron Microscopy

Microstructural Aspects of Adiabatic Shear Failure in Annealed Ti6Al4V

Electromagnetic Detection and Characterization of Tungsten Carbide Inclusions in Non‐Ferromagnetic Alloys

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