The Microstructural Origin of Sinuous Flow in Metal Cutting

2018 ◽  
Author(s):  
Vandana A. Salilkumar ◽  
Narayan K. Sundaram
Keyword(s):  
Plastic Deformation ◽  
Surface Finish ◽  
High Speed ◽  
Metal Cutting ◽  
Ofhc Copper ◽  
Polycrystalline Aggregate ◽  
High Speed Imaging ◽  
Material Microstructure ◽  
Cutting Simulations

In situ, high-speed imaging experiments have revealed the existence of sinuous flow, a recently discovered mode of chip formation in machining. The origin and consequences of sinuous flow are still being investigated, but it is now known that sinuous flow involves extensive redundant plastic deformation, poor surface finish and paradoxically high cutting forces. Here, we use full-scale simulations to show that microstructure related inhomogeneity is a major cause of sinuous flow. The simulations are conducted in a Lagrangian FE framework, and use a simple pseudograin model to represent the metal workpiece as a polycrystalline aggregate. The model successfully captures all essential features of sinuous flow in metals like OFHC copper and CP aluminum, and points to the importance of including material microstructure in cutting simulations.

In Situ Analysis of Deformation Mechanics of Constrained Cutting Towards Enhanced Material Removal

2019 ◽  
Author(s):  
Yang Guo ◽  
Jisheng Chen ◽  
Amr Saleh
Keyword(s):  
Free Surface ◽  
Surface Finish ◽  
Simple Shear ◽  
Chip Formation ◽  
Material Removal ◽  
High Speed ◽  
Image Correlation ◽  
High Speed Imaging ◽  
Deformation Mechanics

Abstract Chip formation in conventional cutting occurs by deformation that is only partially bounded by the cutting tool. The unconstrained free surface is a complication in determining the deformation of chip formation. The constrained cutting employs a constraining tool in the cutting process to confine the otherwise free surface and enable direct control of the chip formation deformation. A study has been made on the deformation mechanics of plane-strain constrained cutting using high speed imaging and digital image correlation (DIC) methods. For different constrained levels (including unconstrained free cutting), material flow of chip formation is directly observed; strain rate and strain in the chip as well as the subsurface region are quantified; cutting forces are measured; and surface finish are examed. The study shows that chip formation in constrained cutting can occur in two different deformation modes, i.e., simple shear and complex extrusion, depending on the constrained level. Constrained cutting in simple shear regime can reduce strain, reduce cutting force and energy, and improve surface finish compared to free cutting, therefore it is more efficient for material removal than free cutting. Constrained cutting in the complex extrusion regime imposes a significant amount of surface / subsurface deformation and consumes a very high cutting energy, and therefore is not suitable for material removal. Furthermore, the mechanics of chip formation in both free cutting and constrained cutting, especially the roles played by the free surface and the constraining tool, are discussed.

scholarly journals The Effect of the In-Situ Heat Treatment on the Martensitic Transformation and Specific Properties of the Fe-Mn-Si-Cr Shape Memory Alloys Processed by HSHPT Severe Plastic Deformation

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4621
Author(s):  
Carmela Gurau ◽  
Gheorghe Gurau ◽  
Felicia Tolea ◽  
Bogdan Popescu ◽  
Mihaela Banu ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
High Pressure ◽  
Severe Plastic Deformation ◽  
High Speed ◽  
High Pressure Torsion ◽  
Electron Interaction ◽  
Sudden Increase ◽  
Neel Temperature ◽  
Néel Temperature

This work focuses on the temperature evolution of the martensitic phase ε (hexagonal close packed) induced by the severe plastic deformation via High Speed High Pressure Torsion method in Fe57Mn27Si11Cr5 (at %) alloy. The iron rich alloy crystalline structure, magnetic and transport properties were investigated on samples subjected to room temperature High Speed High Pressure Torsion incorporating 1.86 degree of deformation and also hot-compression. Thermo-resistivity as well as thermomagnetic measurements indicate an antiferromagnetic behavior with the Néel temperature (TN) around 244 K, directly related to the austenitic γ-phase. The sudden increase of the resistivity on cooling below the Néel temperature can be explained by an increased phonon-electron interaction. In-situ magnetic and electric transport measurements up to 900 K are equivalent to thermal treatments and lead to the appearance of the bcc-ferrite-like type phase, to the detriment of the ε(hcp) martensite and the γ (fcc) austenite phases.

Some Observations on How Mechanochemical Effect Determines Deformation Mode and Chip Morphology in Cutting of Metals

2019 ◽  
Author(s):  
Tatsuya Sugihara ◽  
Mojib Saei ◽  
Koushik Viswanathan ◽  
Anirudh Udupa
Keyword(s):  
High Speed ◽  
Chip Morphology ◽  
Deformation Mode ◽  
Flow Mode ◽  
High Speed Imaging ◽  
Mechanochemical Effect ◽  
Workpiece Surface ◽  
Buckling Instability ◽  
Smooth Flow

Abstract We analyze unsteady plastic flow modes in cutting of metals using high-speed imaging of the deformation zone, in situ. For metals which exhibit high levels of strain hardening, the commonly assumed steady (smooth) flow is inherently unstable. Instead, the cutting is characterized by unsteady sinuous flow, with large-amplitude folding, that is triggered by a plastic buckling instability linked to the material microstructure. A mechanochemical effect caused by Al-Alcohol chemical reaction on workpiece surface, which is coupled to the unsteady flow mode, is highlighted. Experimental results reinforce the hypothesis pertaining to flow stability governing the deformation mode and chip type.

scholarly journals In situ analysis of flow dynamics and deformation fields in cutting and sliding of metals

2015 ◽  
Vol 471 (2178) ◽  
pp. 20150194 ◽  
Author(s):  
Yang Guo ◽  
W. Dale Compton ◽  
Srinivasan Chandrasekar
Keyword(s):  
Material Removal ◽  
High Speed ◽  
Ductile Failure ◽  
Rake Angle ◽  
Flow Dynamics ◽  
High Speed Imaging ◽  
Image Velocimetry ◽  
Material Forming ◽  
Continuous Chip

The flow dynamics, deformation fields and chip-particle formation in cutting and sliding of metals are analysed, in situ , using high-speed imaging and particle image velocimetry. The model system is a brass workpiece loaded against a wedge indenter at low speeds. At large negative rake angles, the flow is steady with a prow of material forming ahead of the indenter. There is no material removal and a uniformly strained layer develops on the workpiece surface—the pure sliding regime. When the rake angle is less negative, the flow becomes unsteady, triggered by formation of a crack on the prow free surface and material removal ensuing—the cutting regime. The strain on the prow surface at crack initiation is found to be constant. Chip morphologies, such as discrete particle, segmented chip and continuous chip with mesoscale roughness, are shown to arise from a universal mechanism involving propagation of the prow crack, but to different distances towards the indenter tip. The simple shear deformation in continuous chip formation shows small-angle oscillations also linked to the prow crack. Implications for material removal processes and ductile failure are discussed.

scholarly journals In-situ characterization of laser-powder interaction and cooling rates through high-speed imaging of powder bed fusion additive manufacturing

2017 ◽  
Vol 135 ◽  
pp. 385-396 ◽  
Author(s):  
Umberto Scipioni Bertoli ◽  
Gabe Guss ◽  
Sheldon Wu ◽  
Manyalibo J. Matthews ◽  
Julie M. Schoenung
Keyword(s):  
Additive Manufacturing ◽  
High Speed ◽  
Powder Bed Fusion ◽  
In Situ Characterization ◽  
High Speed Imaging ◽  
Cooling Rates ◽  
Powder Bed

High Speed Imaging Study of the Dynamics of Ultrasonic Bubbles at a Liquid-Solid Interface

2013 ◽  
Vol 765 ◽  
pp. 230-234 ◽  
Author(s):  
Dong Yue Tan ◽  
Jia Wei Mi
Keyword(s):  
High Speed ◽  
Primary Dendrite ◽  
Imaging Study ◽  
High Speed Imaging ◽  
X Ray ◽  
Dendrite Fragmentation ◽  
X Ray Imaging ◽  
Wave Induced ◽  
Photon Source

High speed imaging, including the ultrafast synchrotron X-ray imaging facility at the beamline 32-ID-B of the Advanced Photon Source (APS), was used to study in-situ (1) the dynamics of ultrasonic bubbles inside a water suspension with an acoustic field of varied pressure; and (2) the interaction of a pulsing bubble at a primary dendrite arm tip inside a succinonitrile-1wt% camphor organic transparent alloy. A simple finite element based model was developed to simulate the stress distribution inside the dendrite due to the pulsing of the ultrasonic bubble, providing more evidence for understanding quantitatively the ultrasonic wave induced dendrite fragmentation phenomenon.

Chip Formation in High-Speed Cutting of Copper and Aluminum

1963 ◽  
Vol 85 (4) ◽  
pp. 365-372 ◽  
Author(s):  
K. J. Trigger ◽  
B. F. von Turkovich
Keyword(s):  
Plastic Deformation ◽  
Chip Formation ◽  
High Speed ◽  
Metal Cutting ◽  
Initial Temperature ◽  
High Speed Machining ◽  
High Speed Cutting ◽  
Work Material ◽  
On Chip ◽  
Cutting Behavior

This paper presents metal-cutting data for the high-speed machining of copper and aluminum, each at two levels of purity, and over a range of workpiece temperatures from −326 deg F (80 deg K) to 550 deg F (560 deg K). It has been found that cutting behavior is influenced by purity of work material, its initial temperature, and extent of tool-chip contact. The influence of plastic deformation on chip hardness has been found to be intimately associated with the purity of the work material.

scholarly journals THE INFLUENCE OF MATERIAL MICROSTRUCTURE ON THE CHIP FORMING PROCESS

2014 ◽  
Vol 5 (1) ◽  
Author(s):  
Pavel Kovač ◽  
Borislav Savković ◽  
Lepa Siđanin ◽  
Ondrej Lukač ◽  
Ildiko Mankova
Keyword(s):  
Plastic Deformation ◽  
Chemical Composition ◽  
Chip Formation ◽  
Metal Cutting ◽  
Crack Formation ◽  
Forming Process ◽  
Material Microstructure ◽  
Workpiece Surface ◽  
Deformation And Fracture ◽  
Extensive Plastic Deformation

For a number of alloys the process of metal cutting is accompanied by extensive plastic deformation and fracture. In the paper we investigate quick stop samples of the chip formation of materials with different chemical composition and microstructure. The type of chip formation is classified according to the mechanism of crack formation and propagation. During cutting, most samples that are used, quasi-continuous chips with built-up edge (BUE) are obtained. The formation of BUE is undesirable since it is a highly deformed body with a semi stable top which periodically breaks away giving rise to poor workpiece surface quality.

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