Characterization of the deformation field in large-strain extrusion machining

Cai, Songlin; Chen, Y.; Ye, G.G.; Jiang, Mingming; Wang, H.Y.; Dai, L.H.

doi:10.1016/j.jmatprotec.2014.08.022

Cited by 40 publications

(13 citation statements)

References 27 publications

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“…Indeed, optical microscopy can easily be coupled with high speed imaging and thus offer a way to work around the two difficulties mentioned in the above. The use of Digital Image Correlation (DIC) has enabled the computation of strains and strain rates at microscale and low cutting speed (V c = 6.10 −4 m.min −1 ) along continuous chips in [13] and at higher speed (V c = 6 m.min −1 ) in serrated chips in [15,44]. Nevertheless, this technique requires unblurred images and is thus often used at low-to-moderate cutting speed.…”

Section: Introductionmentioning

confidence: 99%

A coupled in-situ measurement of temperature and kinematic fields in Ti-6Al-4V serrated chip formation at micro-scale

Harzallah

Pottier

Gilblas

et al. 2018

International Journal of Machine Tools and Manufacture

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The present paper describes and uses a novel bi-spectral imaging apparatus dedicated to the simultaneaous measurement of kinematic and thermal fields in orthogonal cutting experiment. Based on wavelength splitting, this device is used to image small scale phenomenon (about 500×500µm area) involved in the generation of serrated chips from Ti-6Al-4V titanium alloy. Small to moderate cutting speeds are investigated at 6000 images per second for visible spectrum and 600 images per second for infrared measuresments. It allows to obtain unblurred images. A specific attention is paid to calibration issue including optical distortion correction, thermal calibration and data mapping. A complex post-processing procedure based on DIC and direct solution of the heat diffusion equation is detailed in order to obtain strain, strain-rate, temperature and dissipation fields from raw data in a finite strains framework. Finally a discussion is addressed and closely analyzes the obtained results in order to improve the understanding of the segment generation problem from a kinemtatic standpoint but also for the first time from an energetic standpoint.

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Section: Introductionmentioning

confidence: 99%

A coupled in-situ measurement of temperature and kinematic fields in Ti-6Al-4V serrated chip formation at micro-scale

Harzallah

Pottier

Gilblas

et al. 2018

International Journal of Machine Tools and Manufacture

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show abstract

“…The tool with a precut depth t 0 is cutting the workpiece at the cutting speed V 0 , and the chip thickness t c is controlled by the constraint in HSEM. As for free machining (FM), where the constraint is useless, the chip thickness t * c is a materialdependent parameter [28]. The wedge-shaped tool with a rake angle α is machining the cutting layer.…”

Section: Methodsmentioning

confidence: 99%

“…Chandrasekar and co-workers further devised a large-strain extrusion machining (LSEM) apparatus to fabricate ultrafine grain materials (UFGs) at a low cutting speed [27]. Recently, inspired by the works of Chiffre and Chandrasekar, Dai et al developed a high-speed extrusion machining (HSEM) device to research the effect of constraint on the chip formation during HSM [28]. They stated that the chip morphology transforms from serrated to continuous chips once the constraint extrusion factor is equal to or greater than a certain value [29].…”

Section: Introductionmentioning

confidence: 99%

Enhancing surface integrity by high-speed extrusion machining

Liu

Cai

Shang

et al. 2016

Int J Adv Manuf Technol

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High-speed machining (HSM) is an advanced machining technology to form components. However, the poor surface integrity tends to appear due to chip flow instability in HSM. It is found that the surface integrity results from the competition of shear deformation instability between in primary shear zone (PSZ) and in separating shear zone (SSZ). To improve the surface integrity of machined components, the systematic high-speed extrusion machining (HSEM) experiments of magnesium alloy AZ31B with different constraint extrusion factors (CEFs) were carried out. The instability of shear deformation in PSZ is suppressed, and the microwaves on machined surface disappear when CEF is equal to or larger than a certain value. The measurements of the machined surface show that an improvement of surface integrity is achieved if CEF exceeds a certain value. The theoretical model for HSEM was established to elucidate the critical CEF. The underlying physics of surface integrity in HSEM is further revealed. The experimental results verify the validity of the theoretical model.

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“…In order to control the deformation field, Chandrasekar further devised a large strain extrusion machining (LSEM) apparatus by introducing constraint into machining [25]. Dai and co-workers developed the dynamic LSEM and quasi-static LSEM devices to research the suppression of repeated adiabatic shear banding and deformation field [26,27].…”

Section: Introductionmentioning

confidence: 99%

A new method for grain refinement in magnesium alloy: High speed extrusion machining

Liu

Cai

Dai

2016

Materials Science and Engineering: A

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a b s t r a c tMagnesium alloys have received broad attentions in industry due to their competitive strength to density ratio, but the poor ductility and strength limit their wide range of applications as engineering materials. A novel severe plastic deformation (SPD) technique of high speed extrusion machining (HSEM) was used here. This method could improve the aforementioned disadvantages of magnesium alloys by one single processing step. In this work, systematic HSEM experiments with different chip thickness ratios were conducted for magnesium alloy AZ31B. The microstructure of the chips reveals that HSEM is an effective SPD method for attaining magnesium alloys with different grain sizes and textures. The magnesium alloy with bimodal grain size distribution has increased mechanical properties than initial sample. The electron backscatter diffraction (EBSD) analysis shows that the dynamic recrystallization (DRX) affects the grain refinement and resulting hardness in AZ31B. Based on the experimental observations, a new theoretical model is put forward to describe the effect of DRX on materials during HSEM. Compared with the experimental measurements, the theoretical model is effective to predict the mechanical property of materials after HSEM.

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Characterization of the deformation field in large-strain extrusion machining

Cited by 40 publications

References 27 publications

A coupled in-situ measurement of temperature and kinematic fields in Ti-6Al-4V serrated chip formation at micro-scale

A coupled in-situ measurement of temperature and kinematic fields in Ti-6Al-4V serrated chip formation at micro-scale

Enhancing surface integrity by high-speed extrusion machining

A new method for grain refinement in magnesium alloy: High speed extrusion machining

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