Severe plastic deformation (SPD) of titanium at near-ambient temperature

Shankar, M. Ravi; Rao, Balkrishna C.; Lee, Seongeyl; Chandrasekar, Srinivasan; King, Alexander H.; Compton, W. Dale

doi:10.1016/j.actamat.2006.03.056

Cited by 107 publications

(79 citation statements)

References 18 publications

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“…Neither shear band type deformation nor fracture-type deformation happens in the chip formation during lowspeed machining where the cutting speed V 0 is close to the range of the cutting speeds in Fig. 15b, c. The deformation in chips predicted by the presented model is homogeneous in low-speed FM, which is identical with the available experimental observations [29,[50][51][52]. If the cutting speed is further slowed down (e.g., V 0 = 10 −5 m/s), the calculated results in Fig.…”

Section: Effect Of Cutting Speed On Hopf Bifurcation In Fmsupporting

confidence: 79%

“…Based on the results from the literature [4,28], temperature in machining increases with the increasing cutting speed and recrystallization happens when the cutting speed exceeds a certain value. Because recrystallization affects the grain refinement and resulting hardness in HSM [4], ultrafine-grained materials are produced during lowspeed machining (LSM) [29]. For LSM, fracture typically results in the formation of serrated chips [30].…”

Section: Introductionmentioning

confidence: 99%

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Suppression of Hopf bifurcation in metal cutting by extrusion machining

et al. 2016

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Hopf bifurcation is a common phenomenon during the metal cutting process, which results in poor surface finish of the workpiece and inhomogeneous grain structure in materials. Therefore, understanding and controlling Hopf bifurcation in metal cutting are necessary. In this work, the systematic low-speed extrusion machining experiments were conducted to suppress Hopf bifurcation phenomenon. It is found that the suppression of Hopf bifurcation is achieved with the increasing constraint extrusion degree. In order to reveal the mechanism of the suppression of Hopf bifurcation, a new nonlinear dynamic model for extrusion machining is developed where the convection, the diffusion, the extrusion of constraint, the thermal-softening deformation and the fracture-type damage are included. the present theoretical model is effective to characterize the suppression of Hopf bifurcation in metal cutting. Based on the numerical calculation of the theoretical model, the mechanisms underlying in extrusion machining are further revealed: Fracture-type deformation is more important than the thermal-softeningtype deformation in low-speed extrusion machining; however, the thermal-softening-type deformation is the primary deformation mode for high-speed extrusion machining.

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Section: Effect Of Cutting Speed On Hopf Bifurcation In Fmsupporting

confidence: 79%

Section: Introductionmentioning

confidence: 99%

Suppression of Hopf bifurcation in metal cutting by extrusion machining

et al. 2016

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“…Chip formation by machining emerged as our choice of method for severe plastic deformation because of its versatility to impart large range of strain and strain-rate in a single deformation pass in a range of material systems [19][20][21][22][23][24][25]. This allowed us to scan across wide ranges of strainrate (~10 1 -10 3 /s) and strains while still creating fully-dense bulk samples that were still large 5 enough for reliable thermal and mechanical analysis.…”

Section: Experimental Methodsmentioning

confidence: 99%

Effect of strain rate in severe plastic deformation on microstructure refinement and stored energies

Shekhar¹,

Cai²,

Basu³

et al. 2011

J. Mater. Res.

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The interplay of large strain and large strain-rate during high rate severe plastic deformation (HR-SPD) leads to dynamic temperature rise in situ that engenders a recovered microstructure whose characteristics is not just a function of the strain, but also of the strain-rate and the coupled temperature rise during the deformation. In this paper, we identify three classes of microstructures characterized by multi-stage recovery phenomena, that take place during the high strain-rate SPD of Cu. It is found that the first stage of this recovery is similar to the first stage of static recovery which is characterized mainly by annihilation of dislocations. Second stage starts around 360K and was characterized by dislocations getting arranged in tight cell boundaries and eventually into sub-grain. Recovery stages were found to be followed by a stage of grain growth and recrystallization when the temperature in the deformation zone approaches 480K.

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“…It is difficult to attain such ultra-fine grain structures in titanium alloys because of the very rapid rate of grain growth experienced in these alloys, especially at high temperature. However, severe plastic deformation (SPD) techniques such as equal channel angular pressing or high pressure torsion have been utilized to devise sub-micron or even nano-scale structures, albeit only on laboratory scale [1][2]. The major problems encountered with these processes are the limitations placed on size, dimensions and geometry of the components to be manufactured.…”

Section: Introductionmentioning

confidence: 99%

Strain-induced phase transformation during thermo-mechanical processing of titanium alloys

Dehghan-Manshadi

Dippenaar

2012

Materials Science and Engineering: A

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Strain-induced phase transformation studies have been conducted in a Ti-6Al-2Sn-4Zr-6Mo alloy. This alloy was subjected to b sub-transus deformation upon slow cooling from the b-phase field and the effect of strain on the extent and morphology of the phase transformation during hot-deformation was determined. In addition, the transformation kinetics and the morphology of the newly formed a-phase were studied following deformation under different cooling conditions. By applying strain, the rate of the b-to-a phase transformation increased significantly during deformation as well as during slow cooling following deformation. This increase in the kinetics of the b-to-a transformation can be ascribed to straininduced phase transformation. Also, the extent of deformation of the b-phase had a marked effect on the resulting morphology and size of the newly formed a-phase. Transformation of un-deformed b-phase rendered a-phase of acicular morphology only. However, following deformation of the b-phase, acicular as well as globular a-phase morphologies have been observed upon cooling. alloy. This alloy was subjected to β sub-transus deformation upon slow cooling from the β-phase field and the effect of strain on the extent and morphology of the phase transformation during hot-deformation was determined. In addition, the transformation kinetics and the morphology of the newly formed D-phase were studied following deformation under different cooling conditions. By applying strain, the rate of the β-to-α phase transformation increased significantly during deformation as well as during slow cooling following deformation. This increase in the kinetics of the E-to-D transformation can be ascribed to strain-induced phase transformation. Also, the extent of deformation of the β-phase had a marked effect on the resulting morphology and size of the newly-formed D-phase. Transformation of un-deformed β-phase rendered D-phase of acicular morphology only. However, following deformation of the β-phase, acicular as well as globular D-phase morphologies have been observed upon cooling.

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Severe plastic deformation (SPD) of titanium at near-ambient temperature

Cited by 107 publications

References 18 publications

Suppression of Hopf bifurcation in metal cutting by extrusion machining

Suppression of Hopf bifurcation in metal cutting by extrusion machining

Effect of strain rate in severe plastic deformation on microstructure refinement and stored energies

Strain-induced phase transformation during thermo-mechanical processing of titanium alloys

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