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.

scholarly journals Simulation of plastic deformation and destruction in the process of chip formation

2018 ◽  
Vol 211 ◽  
pp. 17007
Author(s):  
Tanel Tärgla ◽  
Jüri Olt ◽  
Olga Liivapuu
Keyword(s):  
Plastic Deformation ◽  
Formation Process ◽  
Chip Formation ◽  
Rheological Model ◽  
Metal Cutting ◽  
Depth Of Cut ◽  
Key Factors ◽  
Local Zone ◽  
Complex Process ◽  
Relaxing Medium

Metal cutting is a complex process in which several mechanisms are at work simultaneously. The mathematical modelling allows carrying out research into the optimization of machining conditions. This work examines the simulation of chip formation during the process of cutting. The studies demonstrated that the chip formation process, taking into account the plastic deformation and destruction of metal in the local zone, is most appropriately represented by a rheological model in the form of a series connection of elasticductile- plastic relaxing medium of Ishlinskiy (reflecting the process of primary deformation of metal from the cut off layer) and the medium of Voigt with two elastic-dissipative elements (representing the process of deformation and frictions from the convergent shaving). The attained complex rheological model served as the basis for constructing a representative dynamic model for the chip formation process. The key factors that govern the chip formation have been taken into account, such as tool vibration frequency and amplitude, depth of cut, feed rate.

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.

On the Metal Physical Considerations in the Machining of Metals

1972 ◽  
Vol 94 (4) ◽  
pp. 1215-1224 ◽  
Author(s):  
S. Ramalingam ◽  
J. T. Black
Keyword(s):  
Plastic Deformation ◽  
Strain Hardening ◽  
Chip Formation ◽  
Metal Cutting ◽  
Dynamic Equilibrium ◽  
Experimental Studies ◽  
Second Phase ◽  
Transmission Electron ◽  
Second Phase Particles ◽  
Strain Hardening Behavior

Experimental studies of plastic deformation produced during metal cutting have shown that a dynamic equilibrium is established between strain hardening and recovery during chip formation. Recrystallization studies on interrupted cut specimens show that the chip is formed by shear on a thin plane or surface which segments the chip into a lamella structure. Scanning and transmission electron microscopy studies on the lateral surfaces of prepolished interrupted cut specimens substantiate the evidence obtained from the recrystallization studies. The chip formation process has thus been found to be strongly sensitive to the metal physics and defect strticture of the material undergoing plastic deformation. The important variables involving dislocation interactions during chip formation are the number and orientation of operable slip systems, certain characteristic dislocation parameters such as stacking fault energy, the interaction of dislocations with vacancies and solute atoms or with second phase particles (both coherent and noncoherent types), the short and long range order of the material, and the temperature of the deformation, all of which affect the strain hardening behavior of the material. In addition, those factors which govern the kinetics of dynamic recovery such as outright collision of dislocation segments, cross slip, and climb induced by a supersaturation of point defects produced in the course of deformation must be considered.

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.

Shear Stress in Metal Cutting

1970 ◽  
Vol 92 (1) ◽  
pp. 151-157 ◽  
Author(s):  
B. F. Von Turkovich
Keyword(s):  
Plastic Deformation ◽  
Shear Stress ◽  
Chip Formation ◽  
Main Parameter ◽  
Metal Cutting ◽  
High Strain ◽  
Energy Requirement ◽  
Large Strains ◽  
Dislocation Theory ◽  
Rate Processes

Since the shear stress is the main parameter influencing the energy requirement in machining, the estimation of this stress remains one of the principal problems in the theory of chip formation. An insight in the behavior of the shear stress can be obtained by considering the process of plastic deformation from the viewpoint of dislocation theory. The theory is developed for high strain rate processes and very large strains.

Deformation in Orthogonal Cutting

1970 ◽  
Vol 92 (1) ◽  
pp. 93-102 ◽  
Author(s):  
S. Ramalingam
Keyword(s):  
Plastic Deformation ◽  
Chip Formation ◽  
Deformation Process ◽  
Metal Cutting ◽  
Orthogonal Cutting ◽  
Cutting Process ◽  
Shear Surface ◽  
Grid Deformation ◽  
Plastic Deformation Process ◽  
Surface Active

This paper examines the plastic deformation process involved in chip formation during orthogonal cutting. Results of the grid deformation studies carried out on polymeric workpieces are reported. Chip formation is shown to result from the action of a curved shear surface, and it is shown that the configuration of the deformation volume during orthogonal cutting is fully determined by the orientation and curvature of the shear surface active during the cutting process. Implications of this model in metal cutting are discussed.

On Wedge Indentation and Its Relationship With Incipient Plastic Deformation in Metal Cutting

1977 ◽  
Vol 99 (3) ◽  
pp. 702-707 ◽  
Author(s):  
K. J. Weinmann
Keyword(s):  
Plastic Deformation ◽  
Plane Strain ◽  
Chip Formation ◽  
Metal Cutting ◽  
Rake Angle ◽  
Wedge Indentation ◽  
Wedge Plate

This paper deals with plane strain indentation of annealed brass by both symmetric and half wedges, and the connection between wedge indentation and incipient chip formation by a positive rake angle tool. Indentation forces and wedge-plate contact lengths were measured, and plastic deformation underneath the indenters was studied by microhardness scanning and discussed. Half-wedge indentations at decreasing distances from the plate corner were shown to result in a transition from wedge indentation to chip formation.

The effect of phase transformations in the process of electrom-beam 3D-printing and post-built heat treatment on the peculiarities of plastic deformation and fracture of high nitrogen Cr-Mn steel

2021 ◽  
pp. 10-17
Author(s):  
E.G. Astafurova ◽  
◽  
K.A. Reunova ◽  
S.V. Astafurov ◽  
M.Yu. Panchenko ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Plastic Deformation ◽  
Electron Beam ◽  
Phase Composition ◽  
Additive Manufacturing ◽  
3D Printing ◽  
Raw Material ◽  
High Nitrogen ◽  
Two Phase ◽  
Deformation And Fracture

We investigated the phase composition, plastic deformation and fracture micromechanisms of Fe-(25-26)Cr-(5-12)Mn-0.15C-0.55N (wt. %) high-nitrogen chromium-manganese steel. Obtained by the method of electron-beam 3D-printing (additive manufacturing) and subjected to a heat treatment (at a temperature of 1150°C following by quenching). To establish the effect of the electron-beam 3D-printing process on the phase composition, microstructure and mechanical properties of high-nitrogen steel, a comparison was made with the data for Fe-21Cr-22Mn-0.15C-0.53N austenitic steel (wt. %) obtained by traditional methods (casting and heat treatment) and used as a raw material for additive manufacturing. It was experimentally established that in the specimens obtained by additive manufacturing method, depletion of the steel composition by manganese in the electron-beam 3D-printing and post-built heat treatment contributes to the formation of a macroscopically and microscopically inhomogeneous two-phase structure. In the steel specimens, macroscopic regions of irregular shape with large ferrite grains or a two-phase austenite-ferrite structure (microscopic inhomogeneity) were observed. Despite the change in the concentration of the basic elements (chromium and manganese) in additive manufacturing, a high concentration of interstitial atoms (nitrogen and carbon) remains in steel. This contributes to the macroscopically heterogeneous distribution of interstitial atoms in the specimens - the formation of a supersaturated interstitial solid solution in the austenitic regions due to the low solubility of nitrogen and carbon in the ferrite regions. This inhomogeneous heterophase (ferrite-austenite) structure has high strength properties, good ductility and work hardening, which are close to those of the specimens of the initial high-nitrogen austenitic steel used as the raw material for additive manufacturing.

Study of Crack Resistance of Layers Applied by Laser Surface Cladding

2014 ◽  
Vol 682 ◽  
pp. 410-413
Author(s):  
S.N. Namazov ◽  
E.D. Rzayev ◽  
V.F. Jivishov
Keyword(s):  
Chemical Composition ◽  
Crack Initiation ◽  
Crack Resistance ◽  
Crack Formation ◽  
Laser Surface ◽  
Surface Cracks ◽  
Welding Technology

The paper describes the crack initiation in the layers which were applied by laser surface cladding. The paper investigates the influence of the chemical composition of layer materials and welding technology on the tendency of the crack formation. Proposed method can dramatically reduce the formation of surface cracks in the applied layers.

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