INFLUENCE OF STRAIN ACCUMULATION ON MICROSTRUCTURE OF ALUMINUM 1100 IN THE TWIST EXTRUSION

2008 ◽  
Vol 22 (18n19) ◽  
pp. 2858-2865 ◽  
Author(s):  
S. A. A. AKBARI MOUSAVI ◽  
A. R. SHAHAB
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
Cross Section ◽  
Strain Distribution ◽  
Metal Flow ◽  
Experimental Tests ◽  
Strain Accumulation ◽  
Twist Extrusion ◽  
Simulation Results ◽  
Metallographic Images

Nowadays, Severe Plastic Deformation (SPD) methods are at the focus of material researchers and among these methods, Twist Extrusion (TE) is one of promising ones to pave the way of commercialization. In this Investigation the magnitude of strain distribution along 4 selected paths of sample after 3 passes of Twist Extrusion were investigated by computer simulation and its influence on aluminum 1100 microstructure by experimental tests. ABAQUS 6.5 software based on FEM was applied for the former and 70 mm length samples with cross-section of 18*28 mm were exploited for the latter. According to the simulation results, corner, middle of small side, middle of long side and center of the cross-section are placed from maximum to minimum magnitude of strain respectively. Theses achievements were verified with metallographic images in aspect of metal flow and grain size as well.

scholarly journals The Chosen Aspects of Skew Rolling of Hollow Stepped Shafts

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 764
Author(s):  
Jarosław Bartnicki ◽  
Yingxiang Xia ◽  
Xuedao Shu
Keyword(s):  
Cross Section ◽  
Rolling Mill ◽  
Metal Flow ◽  
Experimental Tests ◽  
Rolling Process ◽  
Numerical Control ◽  
Technological Parameters ◽  
Flow Mechanisms ◽  
The Individual ◽  
Skew Rolling

The paper presents chosen aspects of the skew rolling process of hollow stepped products with the use of a skew rolling mill designed and manufactured at the Lublin University of Technology. This machine is characterized by the numerical control of spacing between the working rolls and the sequence of the gripper axial movement, which allows for the individual programming of the obtained shapes of parts such as stepped axles and shafts. The length of these zones and the values of possibly realizable cross-section reduction and obtained outlines are the subject of this research paper. The chosen results regarding the influence of the technological parameters used on the course of the process are shown in the present study. Numerical modelling using the finite element method in Simufact Forming, as well as the results of experimental tests performed in a skew rolling mill, were applied in the conducted research. The work takes into account the influence of cross-section reduction of the hollow parts and the feed rate per rotation on the metal flow mechanisms in the skew rolling process. The presented results concern the obtained dimensional deviations and changes in the wall thickness determining the proper choice of technological parameters for hollow parts formed by the skew rolling method. Knowledge about the cause of the occurrence of these limitations is very important for the development of this technology and the choice of the process parameters.

New Type of Device for Achievement of Grain Refinement in Metal Strip

2015 ◽  
Vol 1127 ◽  
pp. 91-97 ◽  
Author(s):  
Stanislav Rusz ◽  
Lubomír Čížek ◽  
Vít Michenka ◽  
Jan Dutkiewicz ◽  
Michal Salajka ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
Severe Plastic Deformation ◽  
Cross Section ◽  
Circular Cross Section ◽  
Ultrafine Grain ◽  
Metallic Materials ◽  
Forming Process ◽  
Fine Grain ◽  
Extrusion Technology

DRECE - Dual Rolls Equal Channel Extrusion" (dual rolls pressure combined with equal channel extrusion) method is used for production of metallic materials with very fine grain size (hereinafter referred to as UFG structure - Ultrafine Grain Size). During the actual forming process the principle of severe plastic deformation is used. The device is composed of the following main parts: “Nord” type gearbox, electric motor with frequency speed converter, multi-plate clutch, feed roller and pressure rollers with regulation of thrust, and of the forming tool itself – made of Dievar steel type. Metallic strip with dimensions 58×2×1000 mm (width x thickness x length) is inserted into the device. During the forming process the main cylinder in synergy with the pressure roller extrude the material through the forming tool without any change of cross section of the strip. In this way a significant refinement of grain is achieved by severe plastic deformation. This method is used for various types of metallic materials, non-ferrous metals and their alloys. Forming process is based on extrusion technology with zero reduction of thickness of the sheet metal with the ultimate aim - achieving a high degree of deformation in the formed material. The DRECE device is also being verified from the viewpoint of achievement of a UFG structure in a blank of circular cross-section (wire) with diameter of ø 8 mm × 1000 mm (length).

Theoretical Justification of the Longitudinal Rolling Method of the Thick Sheets by the Severe Shear Deformation

2020 ◽  
Vol 299 ◽  
pp. 617-621
Author(s):  
Danis Nukhov ◽  
Andrey O. Tolkushkin
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
Metal Forming ◽  
Large Strain ◽  
Metal Flow ◽  
Coarse Grained ◽  
Theoretical Justification ◽  
Longitudinal Rolling ◽  
Steel Sheets ◽  
Rolling Method

Severe plastic deformation (SPD) methods are based on obtaining materials with a grain size of about 100 nm by means of large strain. The SPD processes provide conditions for non-monotonic deformation of the billetsб due to the redistribution of metal macro-flows during shear or alternating strain. Numerous studies have proved the possibility of obtaining high total strain degree for a single SPD cycle. Traditional metal forming processes, such as rolling, implement monotonic deformation behaviorб due to one directional metal flow. In the process of longitudinal rolling, a banded coarse-grained structure with uneven distribution of properties in the volume of the processed metal is observed. The idea of ensuring the SPD in the process of longitudinal rolling of steel sheets is promising. The idea can be realized by the development of deformation tools and modes, which provide redistribution of metal macro-flows not only in the longitudinal but also in the transverse directions of the deformation zone.

The improvement of stress correction in post-necking tension of cylindrical specimen

2019 ◽  
Vol 54 (3) ◽  
pp. 209-222 ◽  
Author(s):  
Junfu Chen ◽  
Zhiping Guan ◽  
Pinkui Ma ◽  
Zhigang Li ◽  
Xiangrui Meng
Keyword(s):  
Cross Section ◽  
Strain Distribution ◽  
Prediction Accuracy ◽  
Inverse Method ◽  
Cylindrical Specimen ◽  
Analytical Models ◽  
Large Strains ◽  
Stress And Strain ◽  
Simulation Results ◽  
Prediction Capability

In post-necking tension of cylindrical specimen, the stress corrections based on the current analytical models have relatively significant errors at large strains. In this study, the prediction capability of these models involving Bridgman model, Siebel model and Chen model is evaluated by performing a series of finite element simulations of uniaxial tension of cylindrical specimen with different hardening exponents varied from 0.05 to 0.3. Numerical analysis of stress and strain distributions on the necking cross section indicates that the considerable errors of the corrected stresses corresponding to large strains might be mainly attributed to the assumption of uniform strain distribution on the necking cross section in these analytical models. The modification strategies of these models are presented in order to improve their prediction accuracy of post-necking stresses, taking geometrical configuration of neck and material properties into consideration. Accordingly, the modification formulas are proposed based on simulation results, involving the radius of cross section of neck and the hardening exponent. Finally, these formulas are used to correct the stresses in the post-necking tension of Q345 cylindrical specimen, which are compared with the stresses identified through inverse method. The results indicate that the modified models significantly improve the prediction accuracy of post-necking stresses at large strains.

Effect of Internal Pressure and Dent Depth on Strain Distribution of Pressurized Pipe Subjected to Indentation

2013 ◽  
Vol 376 ◽  
pp. 135-139 ◽  
Author(s):  
Maziar Ramezani ◽  
Thomas Rainer Neitzert
Keyword(s):  
Plastic Deformation ◽  
Internal Pressure ◽  
Cross Section ◽  
Strain Distribution ◽  
Fe Simulation ◽  
Circular Cross Section ◽  
Numerical Results ◽  
Rectangular Shape ◽  
Longitudinal Strains ◽  
Dent Depth

A dent in a pipeline is a permanent plastic deformation of the circular cross section of the pipe. This paper discusses numerical results obtained from finite element (FE) simulation of pressurized pipe subjected to radial denting by a rigid indenter. Dent produced by rectangular shape indenter is assessed and the strain distribution of the pipe is investigated. The effect of internal pressure and dent depth on the distribution of strain is also studied. The results show that the circumferential and longitudinal strains increase with increasing the internal pressure and the depth of the dent. Numerical results are compared with an empirical theoretical model in order to demonstrate the accuracy of the analysis.

Finite Volume Simulation in Porthole Dies Extrusion of Aluminum Profiles

2011 ◽  
Vol 291-294 ◽  
pp. 290-296
Author(s):  
Lei Cheng ◽  
Shui Sheng Xie ◽  
You Feng He ◽  
Guo Jie Huang ◽  
Yao Fu
Keyword(s):  
Numerical Simulation ◽  
Finite Volume ◽  
Cross Section ◽  
Process Analysis ◽  
Flow Behavior ◽  
Metal Flow ◽  
Extrusion Process ◽  
Porthole Die ◽  
Simulation Results ◽  
Aluminum Profiles

FEM simulation of aluminum profiles in porthole die extrusion process using Lagrange mesh description will inevitably bring mesh self-contact, severe grid distortion and frequent remeshing, which will result in the loss of computational accuracy and excessive calculation time. In order to solve the above mentioned problems, numerical simulation of aluminum profiles with large and complicated cross-section in extrusion process was achieved using finite volume method based on Euler mesh description. The metal flow behavior and welding course was investigated in detail, which can provide the theoretical guide for porthole die design and optimization. In addition, extrusion experiment was carried out by numerical simulation results. The experimental extrudate was in good agreement with the simulation results, which laid a good solid foundation for non-steady state extrusion process analysis of large scale and complicated cross-section profiles.

FEM Simulation and Experimental Investigation of Reshaping of Thick Tubes in Different Passes

2009 ◽  
Author(s):  
A. Tajyar ◽  
K. Abrinia
Keyword(s):  
Experimental Investigation ◽  
High Pressure ◽  
High Temperature ◽  
Cold Rolling ◽  
Cross Section ◽  
Fem Simulation ◽  
Experimental Tests ◽  
Industrial Applications ◽  
Simulation Results ◽  
Roll Gap

Recent advances in high temperature and high pressure applications have made significant increase in industrial applications of square and rectangular seamless tubes. In this work, a reshaping process is presented with cold rolling of a circular thick tube into a square cross section between four flat rolls in different passes. The influence of the amount of roll gap reduction in each pass on the final rolled product was investigated. In order to verify the simulation results, several experimental tests were performed. Quantities such as separated force energy, wall thickness, and corner radius of the tube were observed and measured. Obtained results of simulation showed good agreements with the experiment results.

Upper Bound Analysis of the ECAE Process by Considering Circular Cross-Section and Strain Hardening Materials

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
C. J. Luis Pérez ◽  
R. Luri
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Strain Hardening ◽  
Cross Section ◽  
Upper Bound ◽  
Equal Channel Angular Extrusion ◽  
Circular Cross Section ◽  
Experimental Tests ◽  
Extrusion Force ◽  
Deformation Processes

Severe plastic deformation processes have a great deal of importance because of the improvement in mechanical properties of the processed parts as a consequence of the grain size reduction in the material due to the accumulation of deformation. One of the main severe plastic deformation (SPD) processes is called the equal channel angular extrusion (ECAE). Although a large amount of studies, which deal with experimental analysis of processed parts exist, few studies dealing with the force required to perform the process have been developed. In this study, an analytical modeling of the force required to perform the ECAE process has been developed using the upper bound method (UBM). The analytical equations developed take into account the material strain hardening and the ECAE dies with circular cross-section. Moreover, the experimental tests have been performed and the extrusion force has been measured. The UBM and experimental results have been compared showing a great deal of agreement.

scholarly journals Plastic deformation technology of high strength deformed magnesium alloy

2021 ◽  
Vol 25 (6 Part A) ◽  
pp. 4137-4143
Author(s):  
Lu Xiao ◽  
Shutao Xiong
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Slip Surface ◽  
High Strength ◽  
Slip Direction ◽  
Average Grain Size ◽  
Cumulative Strain ◽  
Simulation Results

The traditional plastic deformation technology of magnesium alloys is relatively poor at high temperature, so a plastic deformation technology of high strength wrought magnesium alloys is designed. Firstly, the slip surface and slip direction which affect the properties of magnesium alloy are analyzed, then the rolling finite element is simulated, the simulation results are visualized, and the simulation information required by the user is output. The results show that the temperature rise decreases with the increase of initial deformation temperature, the average grain size decreases and the uniformity of grain size distribution increases gradually due to dynamic recrystallization, and the cumulative strain and strain distribution in the strain field increases gradually with each pass due to the existence of shear stress in the stress field.

scholarly journals Nanodevices Tend to Be Round

Micromachines ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 330
Author(s):  
Georges Pananakakis ◽  
Gérard Ghibaudo ◽  
Sorin Cristoloveanu
Keyword(s):  
Diffusion Process ◽  
Thermal Diffusion ◽  
Cross Section ◽  
Gate Voltage ◽  
Supportive Evidence ◽  
Inversion Mode ◽  
Nanowire Transistor ◽  
Junctionless Transistor ◽  
Simulation Results ◽  
Thermal Diffusion Process

Under several circumstances, a nanowire transistor with a square cross-section behaves as a circular. Taking the Gate-All-Around junctionless transistor as a primary example, we investigate the transition of the conductive region from square to circle-like. In this case, the metamorphosis is accentuated by smaller size, lower doping, and higher gate voltage. After defining the geometrical criterion for square-to-circle shift, simulation results are used to document the main consequences. This transition occurs naturally in nanowires thinner than 50 nm. The results are rather universal, and supportive evidence is gathered from inversion-mode Gate-All-Around (GAA) MOSFETs as well as from thermal diffusion process.

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