Phase Transformation and Its Effect on Flank Wear in Machining Steels

2002 ◽  
Vol 124 (3) ◽  
pp. 659-666 ◽  
Author(s):  
Wonsik Kim ◽  
Patrick Kwon
Keyword(s):  
Electron Microscopy ◽  
Phase Transformation ◽  
Flank Wear ◽  
Wear Behavior ◽  
Carbon Steels ◽  
Phase Identification ◽  
Material Interface ◽  
Austenitic Phase ◽  
Wear Rates ◽  
Flank Surface

In machining, the main wear mechanism on the flank surface of a tool is commonly believed to be abrasive wear [1,9]. Accordingly, work materials with a higher concentration of hard inclusions are expected to develop higher flank wear rates. However, the previous turning experiment [9] with plain carbon steels containing varying amounts of cementite inclusions did not exhibit the expected flank wear behavior. Other imperative phenomenon must be occurring at the tool-work material interface during machining, which diminishes the abrasive action of the cementite inclusions. To investigate this behavior, a series of turning tests with AISI 1045, 1070, and 4340 steels have been conducted; and the newly generated surface layers are examined for phase identification using Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), and Transmission Electron Microscopy (TEM). At high cutting speeds (>200 m/min), flank wear is diminished as the cementite phase at the newly formed surface dissociates and diffuses into the matrix of the austenitic phase. Because the heated austenite phase is cooled extremely rapidly, martensitic and in some case even retained austenitic phases are formed. This is the evidence of phase transformation, which explains the flank wear data observed in [9]. In addition, phase transformation explains the scatter in flank wear data in the literature because the onset of phase transformation depends on the exact composition of the work materials as well as interfacial conditions such as temperature and pressure. This paper reports the experimental evidence of phase transformation and its consequence on flank wear in machining annealed steels.

Friction Induced Strengthening Mechanisms of Magnesia Partially Stabilized Zirconia

1987 ◽  
Vol 109 (3) ◽  
pp. 531-536 ◽  
Author(s):  
V. Aronov
Keyword(s):  
Wear Resistance ◽  
Phase Transformation ◽  
Plastic Strain ◽  
Wear Behavior ◽  
Xrd Analysis ◽  
Stabilized Zirconia ◽  
Near Surface ◽  
Partially Stabilized Zirconia ◽  
Wear Rates ◽  
Frictional Interface

Experimental investigation of the wear behavior of Magnesia Partially Stabilized Zirconia (Mg-PSZ) rubbed against itself showed that up to three orders of magnitude increase in the wear resistance can be achieved in a particular temperature range that depends on both the sliding speed and the ambient temperature. XRD analysis revealed that thermally induced phase transformation takes place on the frictional interface. Surface analysis show that wear rates at maximum wear resistance are controlled by the crack generation kinetics rather than by crack propagation kinetics. The plastic strain before fracture varies with temperature. The maximum plastic strain was observed at the temperature of maximum wear resistance. A phenomenological model is presented that provides an explanation for the wear temperature behavior of Mg-PSZ. The model is based on the following chain of events that takes place on the frictional interface: spatial overheating of the surface areas, phase transformation of the overheated areas, cooling, volume expansion, and development of a compressive stress field in the near surface volumes.

Transmission electron microscopy of worn zirconia surfaces

1998 ◽  
Vol 13 (2) ◽  
pp. 396-405 ◽  
Author(s):  
W. M. Rainforth ◽  
R. Stevens
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Wear Behavior ◽  
Tetragonal Zirconia ◽  
Dry Sliding Wear ◽  
Microstructural Changes ◽  
Wear Rates ◽  
Transmission Electron ◽  
Order Of Magnitude ◽  
Amorphous Surface

The dry sliding wear behavior of 3 mol% tetragonal zirconia polycrystals (3Y-TZP) and a composite containing 20 vol.% SiC whiskers have been examined by transmission electron microscopy. High wear rates for the TZP were associated with dramatic microstructural changes. The extreme outer ∼ 400 nm consisted of an amorphous surface layer containing both alumina and zirconia. Below this, the t-ZrO2 grain size was an order of magnitude smaller than in the starting material. At a depth of 1–2 μm the tetragonal grains had become elongated, with a maximum aspect ratio of 30 : 1. The first monoclinic zirconia was found at a depth of 5 μm. In contrast, the composite exhibited a wear rate 5 orders of magnitude lower, associated with minor microstructural changes.

Predictive Models for Flank Wear on Coated Inserts

1999 ◽  
Vol 122 (1) ◽  
pp. 340-347 ◽  
Author(s):  
Patrick Kwon
Keyword(s):  
Wear Rate ◽  
Predictive Models ◽  
Flank Wear ◽  
Cutting Temperature ◽  
Carbon Steels ◽  
Temperature History ◽  
Interface Temperature ◽  
Second Phase ◽  
Wear Rates ◽  
Hot Rolled

The purpose of this paper is to develop predictive models for flank wear that explicitly incorporate cutting temperature and the physical properties of coatings and work materials. The development of such models can minimize time-consuming machining experiments in predicting tool life by establishing flank wear models that can be applied to wide classes of coated inserts and work materials. To develop such models, a set of experiments was performed to understand the effect on flank wear due to the morphology and amount of the second phase in work materials. The plain carbon steels of AISI designation 1018, 1045, 1065, 1070, and 1095 in hot-rolled (pearlitic) and/or spherodized conditions were turned. The inserts with a single coating of TiN, TiCN, or Al2O3 were used in the cutting experiments. The temperature history at a remote location on the rake face was measured during cutting by using an infrared pyrometer with a fiber optic attachment. This temperature information was used to estimate the steady-state tool-chip interface temperatures using the inverse estimation scheme by Yen and Wright, 1986, ASME J. Eng. Ind., 108, pp. 252–263. The results were then used to predict the work-tool interface temperature using the scheme suggested by Oxley, 1989, The Mechanics of Machining: An Analytical Approach to Assessing Machinability, Wiley, New York, NY, p. 168. The results of this experiment showed that, for the spherodized steels, flank wear per sliding distance (the flank wear rate) increased with the cementite content. For the hot-rolled (pearlitic) steels, no conclusive evidence was found that correlates the flank wear rate with the cementite content. However, for pearlitic steels the wear rates, in general, were shown to increase with the flank temperature while for spherodized steels the rates decrease with the flank temperature. The reason for these trends can be explained by the microstructural difference between pearlitic and spherodized steels; therefore, the semi-empirical models of two-body and three-body wear developed by Rabinowicz (1967) and Rabinowicz et al. (1972) can be applied to describe the flank wear process. [S0742-4787(00)04501-X]

A Novel Approach to Determine the Cutting Temperature Under Consideration of the Tool Wear

2020 ◽  
Author(s):  
Thomas Bergs ◽  
Bingxiao Peng ◽  
Daniel Schraknepper ◽  
Thorsten Augspurger
Keyword(s):  
Temperature Distribution ◽  
Tool Wear ◽  
Wear Surface ◽  
Metal Cutting ◽  
Flank Wear ◽  
Wear Behavior ◽  
Orthogonal Cutting ◽  
Cutting Temperature ◽  
Novel Approach ◽  
Flank Surface

Abstract In metal cutting process, modeling and predicting the tool wear development has been researched for decades. Many efforts have been made to study the cutting temperature as an indicator for the tool wear behavior. However, the determination of the cutting temperature in the critical contact area in process is still a challenge. In order to build temperature-dependent tool wear models, the temperature distribution of the workpiece was captured in this paper by an infrared thermography in orthogonal cutting of Direct Aged Inconel 718 with cemented carbide cutting tool WC-15Co. Instead of studying the temperature in critical cutting zone directly, the workpiece temperature distribution around the flank wear surface was determined inversely with the analytical Jaeger-solution based on the experimental data. The determined maximum cutting temperature on the flank wear surface has been successfully verified by FEM chip formation simulations. By means of this inverse approach, the cutting temperature on the flank surface can be determined as a function of tool wear VB. The experimental results showed that the cutting temperature increased with the increase of the tool wear VB. By means of this method, the temperature on the flank wear surface can be used as an important physical indicator to model and predict the tool wear development in future work.

Rake and Flank Wear Mechanisms of Coated and Uncoated Cemented Carbides

1985 ◽  
Vol 107 (1) ◽  
pp. 68-82 ◽  
Author(s):  
P. A. Dearnley
Keyword(s):  
Electron Microscopy ◽  
Wear Mechanisms ◽  
Flank Wear ◽  
Cemented Carbides ◽  
Al2o3 Ceramic ◽  
Wear Rates ◽  
Interfacial Conditions ◽  
Composite Layers ◽  
Microscopy Techniques ◽  
Scanning Electron

A series of commercially available cemented carbides coated with single or composite layers of TiC, TiN, and Al2O3 were used to cut three types of steel, En8 (∼AISI 1042), En24 (∼AISI 4340), and En9 (∼AISI 1055). For comparison, two uncoated cemented carbides and some Al2O3-ceramic inserts were also tested. The worn surfaces were examined using optical and scanning electron microscopy techniques and tool/work interfacial conditions were evaluated from quick-stop experiments and tool temperature estimates. By linking this information with observed wear rates, various rake and flank wear mechanisms are proposed.

scholarly journals Lath Martensite Microstructure Modeling: A High-Resolution Crystal Plasticity Simulation Study

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 691
Author(s):  
Francisco-José Gallardo-Basile ◽  
Yannick Naunheim ◽  
Franz Roters ◽  
Martin Diehl
Keyword(s):  
High Resolution ◽  
Mechanical Behavior ◽  
Crystal Plasticity ◽  
Lath Martensite ◽  
Three Dimensional ◽  
Building Blocks ◽  
Quantitative Agreement ◽  
Carbon Steels ◽  
Plastic Behavior ◽  
Austenitic Phase

Lath martensite is a complex hierarchical compound structure that forms during rapid cooling of carbon steels from the austenitic phase. At the smallest, i.e., ‘single crystal’ scale, individual, elongated domains, form the elemental microstructural building blocks: the name-giving laths. Several laths of nearly identical crystallographic orientation are grouped together to blocks, in which–depending on the exact material characteristics–clearly distinguishable subblocks might be observed. Several blocks with the same habit plane together form a packet of which typically three to four together finally make up the former parent austenitic grain. Here, a fully parametrized approach is presented which converts an austenitic polycrystal representation into martensitic microstructures incorporating all these details. Two-dimensional (2D) and three-dimensional (3D) Representative Volume Elements (RVEs) are generated based on prior austenite microstructure reconstructed from a 2D experimental martensitic microstructure. The RVEs are used for high-resolution crystal plasticity simulations with a fast spectral method-based solver and a phenomenological constitutive description. The comparison of the results obtained from the 2D experimental microstructure and the 2D RVEs reveals a high quantitative agreement. The stress and strain distributions and their characteristics change significantly if 3D microstructures are used. Further simulations are conducted to systematically investigate the influence of microstructural parameters, such as lath aspect ratio, lath volume, subblock thickness, orientation scatter, and prior austenitic grain shape on the global and local mechanical behavior. These microstructural features happen to change the local mechanical behavior, whereas the average stress–strain response is not significantly altered. Correlations between the microstructure and the plastic behavior are established.

scholarly journals Oxygen Induced Phase Transformation in TC21 Alloy with a Lamellar Microstructure

Metals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 163
Author(s):  
Shu Wang ◽  
Yilong Liang ◽  
Hao Sun ◽  
Xin Feng ◽  
Chaowen Huang
Keyword(s):  
Electron Microscopy ◽  
Phase Transformation ◽  
Oxygen Uptake ◽  
Titanium Alloys ◽  
Electron Backscatter Diffraction ◽  
Lamellar Microstructure ◽  
Α Phase ◽  
Transmission Electron ◽  
The Matrix ◽  
Oxygen Ingress

The main objective of the present study was to understand the oxygen ingress in titanium alloys at high temperatures. Investigations reveal that the oxygen diffusion layer (ODL) caused by oxygen ingress significantly affects the mechanical properties of titanium alloys. In the present study, the high-temperature oxygen ingress behavior of TC21 alloy with a lamellar microstructure was investigated. Microstructural characterizations were analyzed through optical microscopy (OM), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM). Obtained results demonstrate that oxygen-induced phase transformation not only enhances the precipitation of secondary α-phase (αs) and forms more primary α phase (αp), but also promotes the recrystallization of the ODL. It was found that as the temperature of oxygen uptake increases, the thickness of the ODL initially increases and then decreases. The maximum depth of the ODL was obtained for the oxygen uptake temperature of 960 °C. In addition, a gradient microstructure (αp + β + βtrans)/(αp + βtrans)/(αp + β) was observed in the experiment. Meanwhile, it was also found that the hardness and dislocation density in the ODL is higher than that that of the matrix.

Characterization of diamond thin films: Diamond phase identification, surface morphology, and defect structures

1989 ◽  
Vol 4 (2) ◽  
pp. 373-384 ◽  
Author(s):  
B. E. Williams ◽  
J. T. Glass
Keyword(s):  
Electron Microscopy ◽  
Surface Morphology ◽  
Methane Concentration ◽  
Microwave Plasma ◽  
Defect Density ◽  
Diamond Films ◽  
Hydrogen Gas ◽  
Phase Identification ◽  
Diamond Crystals ◽  
Thin Carbon

Thin carbon films grown from a low pressure methane-hydrogen gas mixture by microwave plasma enhanced CVD have been examined by Auger electron spectroscopy, secondary ion mass spectrometry, electron and x-ray diffraction, electron energy loss spectroscopy, and electron microscopy. They were determined to be similar to natural diamond in terms of composition, structure, and bonding. The surface morphology of the diamond films was a function of position on the sample surface and the methane concentration in the feedgas. Well-faceted diamond crystals were observed near the center of the sample whereas a less faceted, cauliflower texture was observed near the edge of the sample, presumably due to variations in temperature across the surface of the sample. Regarding methane concentration effects, threefold {111} faceted diamond crystals were predominant on a film grown at 0.3% CH4 in H2 while fourfold {100} facets were observed on films grown in 1.0% and 2.0% CH4 in H2. Transmission electron microscopy of the diamond films has shown that the majority of diamond crystals have a very high defect density comprised of {111} twins, {111} stacking faults, and dislocations. In addition, cross-sectional TEM has revealed a 50 Å epitaxial layer of β3–SiC at the diamond-silicon interface of a film grown with 0.3% CH4 in H2 while no such layer was observed on a diamond film grown in 2.0% CH4 in H2.

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