scholarly journals Modelling of Grain Size Evolution with Different Approaches via FEM When Hard Machining of AISI 4140

Metals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1296
Author(s):  
Berk Tekkaya ◽  
Markus Meurer ◽  
Sebastian Münstermann
Keyword(s):  
Grain Size ◽  
Hard Turning ◽  
White Layer ◽  
High Hardness ◽  
Machining Process ◽  
Machined Surface ◽  
Size Evolution ◽  
Aisi 4140 ◽  
Fine Microstructure ◽  
Negative Effect

Thermo-mechanical loads during hard turning lead to the formation of so-called White Layers on the machined surface. Characterized by a very fine microstructure and high hardness, White Layers have a negative effect on the fatigue life of a component. The fundamental mechanism for the White Layer formation is the dynamic recrystallization (DRX). Therefore, in the current work, two different DRX models, Helmholtz free energy and Zener-Hollomon, are implemented into Abaqus/Explicit to predict the thickness of the White Layer when hard turning quenched/tempered AISI 4140 and the results are compared with each other. For the simulation of the machining process a Finite Element Method (FEM) model based on the Coupled-Eulerian-Lagrangian (CEL) method is built up. Although both DRX models achieved a very good match between predicted and measured White Layer thickness and grain size evolution on the workpiece rim zone, the Zener-Hollomon model produced more closer agreement.

Finite Element Modeling on Dislocation Density and Grain Size Evolution in Machined Surface

2013 ◽  
Author(s):  
Liqiang Ding ◽  
Xueping Zhang ◽  
C. Richard Liu
Keyword(s):  
Grain Size ◽  
Dislocation Density ◽  
Orthogonal Cutting ◽  
Cutting Speed ◽  
Experimental Tests ◽  
Rake Angle ◽  
Machining Process ◽  
Fe Model ◽  
Machined Surface ◽  
Size Evolution

Machining process usually induces Severe Plastic Deformation (SPD) in the chip and machined surface, which will further lead to rapid increase of dislocation density and alteration of grain size in micro-scale. This paper presents a novel FE model to simulate the dislocation density and grain size evolution in the machined surface and subsurface generated from the orthogonal cutting process of Al6061-T6. A dislocation density model of microstructure evolution is implemented in the FE model as a user-defined subroutine written in FORTRAN. The model can predict the microstructure characteristic in a machined surface. The predicted chip thicknesses, cutting forces, distributions of dislocation density and grain size are verified by the experimental tests of the chip, forces, microstructure and micro-hardness. The predicted results show that the dislocation density decreases along the depths of machined surface; whereas the grain size shows an opposite tendency. Dislocation density in machined surface decreases and grain size increases when cutting speed increases. Higher cutting speeds are associated with thinner deformation layers. Dislocation density in a machined surface decreases initially and then increases with feed rates. Dislocation density increases significantly when cutting tool has a larger negative rake angle. The bigger negative rake angles further lead to the thicker deformation layers in machined surface.

Surface Roughness and Cutting Force Components Evaluation in Hard Turning by Differently Shaped Cutting Tools

2016 ◽  
Vol 862 ◽  
pp. 26-32 ◽  
Author(s):  
Michaela Samardžiová
Keyword(s):  
Surface Roughness ◽  
Cutting Force ◽  
Hard Turning ◽  
Cutting Tool ◽  
Single Point ◽  
Machining Process ◽  
Tool Geometry ◽  
Machined Surface ◽  
Cutting Force Components ◽  
Force Components

There is a difference in machining by the cutting tool with defined geometry and undefined geometry. That is one of the reasons of implementation of hard turning into the machining process. In current manufacturing processes is hard turning many times used as a fine finish operation. It has many advantages – machining by single point cutting tool, high productivity, flexibility, ability to produce parts with complex shapes at one clamping. Very important is to solve machined surface quality. There is a possibility to use wiper geometry in hard turning process to achieve 3 – 4 times lower surface roughness values. Cutting parameters influence cutting process as well as cutting tool geometry. It is necessary to take into consideration cutting force components as well. Issue of the use of wiper geometry has been still insufficiently researched.

scholarly journals Analysis of AISI D2 Steel by using SEM Images

2020 ◽  
Vol 8 (6S) ◽  
pp. 148-155
Keyword(s):  
Hard Turning ◽  
Manufacturing Industry ◽  
White Layer ◽  
Chip Morphology ◽  
Cutting Parameters ◽  
Cutting Condition ◽  
Machined Surface ◽  
Sem Images ◽  
Aisi D2 ◽  
D2 Steel

Hard turning is a new emerging technique in manufacturing industry which involves turning of hard steel having hardness more than 60 HRC. Here in the present work, the objective of the study is steel type ENX160CrMo having hardness 62 HRC. Hard turning were carried out at different cutting parameters and chip hardness and micro- chip SEM images were observed. Micro- machined surface images, observed at different cutting condition to know the relation between chip morphology and micro-structure of the machined surface. White layer formation indicates the reduction in fatigue life was also studied.

Effects of Cutting Speed and Feed Rate on Surface Roughness in Hard Turning of AISI 4140 with Mixed Ceramic Cutting Tool

2018 ◽  
Vol 779 ◽  
pp. 153-158
Author(s):  
Phacharadit Paengchit ◽  
Charnnarong Saikaew
Keyword(s):  
Surface Roughness ◽  
Feed Rate ◽  
Hard Turning ◽  
Cutting Tool ◽  
Cutting Speed ◽  
Machined Surface ◽  
Data Set ◽  
Ceramic Cutting Tool ◽  
Aisi 4140 ◽  
Mixed Ceramic

This work investigated the influences of cutting speed and feed rate on surface roughness in hard turning of AISI 4140 chromium molybdenum steel bar using mixed ceramic inserts Al2O3+TiC under dry condition for automotive industry applications. Turning experiments were conducted by varying cutting speed ranging from 150 to 220 m/min and feed rate ranging from 0.06 to 1 mm/rev. General factorial design was used to analyze the data set of surface roughness and determine statistically significant process factors based on analysis of variance results. The results showed that average surface roughness was significantly affected by feed rate and interaction between cutting speed and feed rate at the level of significance of 0.05. An optimal operating condition for hard turning of AISI 4140 with the ceramic cutting tool that produced a minimum machined surface roughness was obtained at cutting speed of 220 m/min and 0.06 mm/rev.

Characteristics of Residual Stress Profiles in Hard Turned Versus Ground Surfaces With and Without a White Layer

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
A. W. Warren ◽  
Y. B. Guo
Keyword(s):  
Residual Stress ◽  
Compressive Residual Stress ◽  
Hard Turning ◽  
Cutting Tool ◽  
Stress Measurement ◽  
White Layer ◽  
Machining Process ◽  
Tensile Residual Stress ◽  
Stress Profile ◽  
Stress Profiles

Hard turning and grinding are precision processes in many cases for manufacturing various mechanical products. Product performance is highly dependent on the process induced residual stress. However, the basic differences in residual stress profiles generated by hard turning and grinding with and without the presence of a thermal white layer have not been well understood. This study aims to compare basic characteristics of the residual stress profiles using an extensive residual stress measurement for five surface types: hard turned fresh, hard turned with a white layer, ground fresh, ground with a white layer, and as heat treated. The X-ray diffraction data revealed distinct differences in the residual stress profiles for the five surface types. Hard turning with a sharp cutting tool generates a unique “hook” shaped residual stress profile characterized by compressive residual stress at the surface and maximum compressive residual stress in the subsurface, while “gentle” grinding only generates maximum compressive residual stress at the surface. The depth of compressive residual stress in the subsurface by hard turning is much larger than that by grinding. The high hertz pressure induced by the cutting tool in turning is the determining factor for the differences in residual stress. High tensile residual stress associates with the existence of a turned or a ground white layer. The coupled effects of high hertz pressure and rapid temperature change induced by tool wear play an important role in the resultant tensile residual stress. In addition, residual stress by grinding is more scattered than that by turning. Compared with the deterministic influence of machining process on the magnitudes and profiles of residual stress, the effect of heat treatment is minor.

Development of SiO2 Nanolubrication System for Better Surface Quality, more Power Savings and Less Oil Consumption in Hard Turning of Hardened Steel AISI4140

2013 ◽  
Vol 748 ◽  
pp. 56-60 ◽  
Author(s):  
M. Sayuti ◽  
Ahmed A.D. Sarhan ◽  
S. Salem
Keyword(s):  
Power Consumption ◽  
Surface Quality ◽  
Hard Turning ◽  
Cnc Machining ◽  
Machining Process ◽  
Lubrication System ◽  
Turning Process ◽  
Oil Consumption ◽  
Machined Surface ◽  
Machined Surface Quality

In recent years, the energy efficiency improvement has become significant due to rapid consumption of world's energy resources. Particularly in manufacturing industry, hard turning process is one of the most fundamental metal removal processes that require huge power consumption and it could be improved in term of energy usage by many alternatives. At the same time, the improvement in term of machined surface quality is become a need since it would reflect appearance, performance and reliability of the products. As for example in the CNC machining field, one of the solution for this issue is by increasing the effectiveness of the existing lubrication systems as it could improve the machined surface quality, reduce the power required to overcome the friction component in batch production of machining process and reduce the oil consumption. The effectiveness of the lubrication system could be improved by introducing the nanobase lubrication system for much less power consumption as the rolling action of billions units of nanoparticle in the tool chip interface could reduce the cutting forces significantly. In this research work, the possibility of using SiO2 nanobase lubrication system is investigated to reduce the machining power consumption as well as improving surface quality in hard turning process of AISI4140.

scholarly journals 3D FE Modelling of Machining Forces during AISI 4140 Hard Turning

2020 ◽  
Vol 66 (7-8) ◽  
pp. 467-478 ◽  
Author(s):  
Anastasios Tzotzis ◽  
César García-Hernández ◽  
José-Luis Huertas-Talón ◽  
Panagiotis Kyratsis
Keyword(s):  
Hard Turning ◽  
Cutting Speed ◽  
Industrial Applications ◽  
Machining Process ◽  
Depth Of Cut ◽  
Machining Processes ◽  
Fe Modelling ◽  
Machining Force ◽  
Aisi 4140 ◽  
Force Components

Hard turning is one of the most used machining processes in industrial applications. This paper researches critical aspects that influence the machining process of AISI-4140 to develop a prediction model for the resultant machining force-induced during AISI-4140 hard turning, based on finite element (FE) modelling. A total of 27 turning simulation runs were carried out in order to investigate the relationship between three key parameters (cutting speed, feed rate, and depth of cut) and their effect on machining force components. The acquired numerical results were compared to experimental ones for verification purposes. Additionally, a mathematical model was established according to statistical methodologies such as the response surface methodology (RSM) and the analysis of variance (ANOVA). The plurality of the simulations yielded results in high conformity with the experimental values of the main machining force and its components. Specifically, the resultant cutting force agreement exceeded 90 % in many tests. Moreover, the verification of the adequacy of the statistical model led to an accuracy of 8.8 %.

The Effect of Technological Conditions of Hard Turning on the Formation of White Layer

2016 ◽  
Vol 862 ◽  
pp. 96-103 ◽  
Author(s):  
Zoltán Pálmai ◽  
János Kundrák
Keyword(s):  
Hard Turning ◽  
White Layer ◽  
Layer Formation ◽  
Technological Parameters ◽  
Machined Surface ◽  
Border Line ◽  
Measurement Results ◽  
Composition Structure ◽  
Gear Wheels ◽  
White Layer Formation

In fast spreading hard turning occasionally a so-called white layer appears on the machined surface, which is mostly harmful. The formation of white layers and their composition, structure and thickness were investigated in the turning of the inner cylindrical surface of gear wheels made from 20MnCr5 case hardened steel, in order to identify to what extent the technological parameters of turning influence the white layer formation. On the basis of the measurement results it was possible to include border-line technological conditions in an empirical formula with which white layer formation can be avoided.

Investigation of White Layers Formed in Conventional and Cryogenic Hard Turning of Steels

Manufacturing ◽  
2003 ◽  
Author(s):  
Zbigniew Zurecki ◽  
Ranajit Ghosh ◽  
John H. Frey
Keyword(s):  
Residual Stress ◽  
Hard Turning ◽  
Stress Measurement ◽  
White Layer ◽  
Spray Cooling ◽  
Cryogenic Liquid ◽  
Machined Surface ◽  
Machining Speed ◽  
The Impact

Although hard turning of steels has become an accepted industrial practice reducing the extent of grinding, many surface integrity aspects of hard turning require clarification. The striking result of hard turning is the tendency for forming white (non-etching) and dark (overtempered) layers at machined surface. White layers are often associated with residual tensile stresses leading to reduced fatigue strength and poor wear resistance. It has been reported that certain steel compositions, machining conditions, and tools enhance white layers, but no consensus was reached on the nature of white layer and the role of environmental factors. This study examines the impact of cryogenic, liquid nitrogen spray cooling, tool and work materials, as well as machining speed on white layer formation. Results are evaluated using XRD, SEM, EDS, AES, residual stress measurement and microhardness profiling. It is concluded that white layers are a purely thermomechanical phenomenon involving dissolution of low-alloy carbides into austenitic matrix, and catastrophic flow of that 1-phase material resulting in its nano-scale refinement. The depth and extent of the refinement are controlled by cooling, with the cryogenic nitrogen reducing white layer thickness, loss of hardness, and improving residual stress distribution.

scholarly journals Phase transformation and subsurface damage formation in the ultrafine machining process of a diamond substrate through atomistic simulation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Van-Thuc Nguyen ◽  
Te-Hua Fang
Keyword(s):  
Grain Size ◽  
Elastic Recovery ◽  
Vertical Direction ◽  
Substrate Material ◽  
Transformation Process ◽  
Machining Process ◽  
Machined Surface ◽  
Diamond Substrate ◽  
Force Transformation ◽  
Higher Temperature

AbstractThis report explores the effects of machining depth, velocity, temperature, multi-machining, and grain size on the tribological properties of a diamond substrate. The results show that the appearance of graphite atoms can assist the machining process as it reduces the force. Moreover, the number of graphite atoms relies on the machining speed and substrate temperature improvement caused by the friction force. Besides, machining in a machined surface for multi-time is affected by its rough, amorphous, and deformed surface. Therefore, machining in the vertical direction for multi-time leads to a higher rate of deformation but a reduction in the rate of graphite atoms generation. Increasing the grain size could produce a larger graphite cluster, a higher elastic recovery rate, and a higher temperature but a lower force and pile-up height. Because the existence of the grain boundaries hinders the force transformation process, and the reduction in the grain size can soften the diamond substrate material.

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