Loading...
Search for:
low-carbon-steel
0.008 seconds
Total 85 records
Investigation of Microstructure and Mechanical Properties after Performing Cold Rolling and Annealing on Severely Deformed Low Carbon Steel
, M.Sc. Thesis Sharif University of Technology ; Kazeminezhad, Mohsen (Supervisor)
Abstract
According to the conducted research, severe deformation of low-carbon steel sheets using the constrained groove pressing method causes a decrease in grain size and increases the strength and hardness of the sample after one pass. However, continuing this process in subsequent passes does not significantly increase strength and hardness, and sometimes it remains constant. Therefore, in this project, cold rolling has been used to improve the strength of the steel sheet and improve the surface smoothness of the final piece. After severe deformation and rolling due to the high applied strain, the strength of the sample increased and the percentage of its elongation decreased. Therefore,...
Effect of Warm Rolling on The Microstructure and Tensile Properties of Severely Deformed Low Carbon Steel in Grooved Die
, M.Sc. Thesis Sharif University of Technology ; Kazeminejad, Mohsen (Supervisor)
Abstract
In recent years, various research has been done on the severe deformation of low carbon steel sheets. One of the methods used is the pressing in the grooved die, only two passes of the pressing process in the grooved mold have been successful when applied to these sheets, but on the other hand, these two passes also lessen the sheet's ductility while increasing its strength. Due to the fact that the sheet surface produced by the pressing in the grooved die is not entirely smooth, the attempt in this project was to improve the ductility to some extent using warm rolling in addition to the smoothness of the surface using higher temperature while improving the strength or maintain it. To...
Effect of Inter-pass Annealing During Severe Plastic Deformation on Microstructure and Mechanical Properties of Low Carbon Steel
, M.Sc. Thesis Sharif University of Technology ; Kazeminezhad, Mohsen (Supervisor)
Abstract
Low carbon steel is widely used in the automotive industry by improving ductility and minimizing hardness to achieve greater strain. Applying severe plastic deformation to metals and alloys increases strength and decreases ductility. In the process of severe plastic deformation, the pressure is limited in the grooved form. Low carbon steel, after two passes of severe plastic deformation, experiences a rapid drop in strength in addition to ductility, which may indicate the presence of microcracks. Therefore, in this research, annealing between passes during the pressure process in the form of limited grooves has been used so that without a serious decrease in strength, some ductility...
The Effect of Electropulsing on the Mechanical Properties of Cold Rolled Low Carbon Steel
, M.Sc. Thesis Sharif University of Technology ; Kazeminezhad, Mohsen (Supervisor)
Abstract
In this research, low carbon steel rolled under 16%, 33% and 50% deformation and applied under electric pulses. Microstructure investigated by optical microscopy and scanning electron microscopy in order to observe grain size, precipitation size and distribution and hardness measured by Vicker's hardness test, after each electric pulse treatment. I order to investigate microstructure evolution as well as grain size, precipitates and hardness all the species with different deformation percentages applied under electric pulses with different total electric pulse duration, number of pulses and the off time between two successive pulses. To obtain required information about species with...
A Study on Deformation Behavior During Asymmetrical Rolling of Low Carbon Steels and Subsequent Microstructural Phenomena
, M.Sc. Thesis Sharif University of Technology ; Serajzadeh, Siamak (Supervisor)
Abstract
In this study, static recrystallization (Rex) of a low carbon steel after cold rolling has bees simulated under non-isothermal condition by employing cellular automata (CA) method. Symmetric cold rolling and asymmetric cold rolling (ASR) which was arisen by inequality of friction coefficient have been applied as primary cold deformation. Residual stress and strain field after deformation, and temperature rate and distribution of specimens during annealing has been evaluated by employing two different models based on finite element method. Initial microstructure has been developed by haphazardly distribution of grains and topological adjustments were imposed on it. Results of FEM models were...
An Investigation into the Effect of Prestrain Temperature on the Static
Recrystallization of low Carbon Steel
,
M.Sc. Thesis
Sharif University of Technology
;
karimi Taheri, Ali
(Supervisor)
Abstract
In this project the effect of rolling temperature on mechanical properties and microstructure evolution of a low carbon steel was studied. The steel was rolled up to a nominal strain of 67% at three different temperatures consisted of room, blue brittleness, and subzero temperature. Micreohardnessand tensile tests were used to characterize the recrystallization kinetics. Optical and scanning electron microscopic examinations were carried out to evaluate the mechanical, grain size, and the kinetics of static recrystallization by the Avrami equation. The results indicated that the volume fraction of static recrystallization increases with the increase in annealing period. The Avrami exponent...
Investigation of Multistage Static Strain Aging of Low Carbon Steel using Rolling Pre-strain
, M.Sc. Thesis Sharif University of Technology ; karimi taheri, Ali (Supervisor)
Abstract
In the present study, multistage strain aging phenomenon using rolling pre-strain and solution treatment at 680℃ for 40 min was used to study the effect of temperature and inter-pass time (IPT) on the static strain aging behavior of a low carbon steel sheet. The increase in hardness and strength caused by work hardening and the aging at each pass were separately calculated.The samples were rolled and subjected to aging process both in a single pass of 20% rolling reduction in thickness and in four stages consisted of 5% reduction at each stage. The mechanical properties of the samples aged at different time and temperature, were compared. In order to evaluate the effects of pre-strain type,...
, M.Sc. Thesis Sharif University of Technology ; Ghorbani, Mohammad (Supervisor)
Abstract
Phosphating is one of the most procedures as a final surface treatment or pre-treatment (lubrication and Infrastructure color) is done on ferrous and nonferrous alloys. Phosphate coating on the wire drawing, increase speed of drwing, increase die life, increased resistance to abrasion caused by the friction reduction, reduced maintenance costs and improved surface appearance are combustible and conditions. The aim of this study was to evaluate the effects of variables such as temperature, pH bath, the coating bath components concentration on coating properties and optimize calcium zinc phosphate coating on steel wire, for better lubrication and decrease friction in the wire drawing process....
Resistance Spot Welding of Galvanized and Low Carbon Steel Sheet to 5XXX Aluminum Alloy
, M.Sc. Thesis Sharif University of Technology ; Kokabi, Amir Hossein (Supervisor) ; Movahhedi, Mojtaba (Supervisor)
Abstract
Joining between aluminum alloys and steels by resistance spot welding accompanies critical technological and metallurgical difficulties. The main problem is formation of brittle intermetallic compounds (IMC) at the welding interface which results in poor mechanical properties. There are some researches based on the microstructure and mechanical properties of resistace spot welding of aluminum to steel and each of them has tried to enhance the joint properties. Using Zn interlayer is an approach to improve Al to steel resistance spot welding properties. Up to now there is few information on the influence of Zn as an interlayer between steel and aluminum on the Al/Steel dissimilar welding...
Effect of Rapid Annealing on Microstructure and Mechanical Properties of Severely Deformed Low Carbon Steel
, M.Sc. Thesis Sharif University of Technology ; Kazeminezhad, Mohsen (Supervisor)
Abstract
A low-carbon steel, containing 0.05 C, 0.203 Mn and 0.0229 Si (all in wt%) rapidly annealed in temperature range 300 ºC - 900 ºC, after severe plastic deformation (SPD) by constrained groove pressing (CGP). Microstructure evolution was investigated by Scanning Electron and Optical Microscopy. Mechanical properties were evaluated by hardness measurements and Shear Punch Testing (SPT). The result showed a thermal stability at 300 ºC and 400 ºC, which recrystallization did not occurred in these temperatures up to 2 h holding time. By annealing at 500 ºC and 600 ºC, the onset of recrystallization observed after holding times of 10 min and 20 s, respectively. Predicting the kinetic of...
Prediction of Cooling Rate and Thermal Stresses during Cooling on Run-Out Table in Hot Sheet Rolling Process
, M.Sc. Thesis Sharif University of Technology ; Serajzadeh, Siamak (Supervisor)
Abstract
Control of the product manufacturing and evaluating its behavior during deformation is one of the most important issues in hot deformation, especially hot rolling. One of the factors affecting on quality of hot rolled steel strips is the flatness after run-out table cooling.Distortion in a steel strip results from non-uniform temperature profile as the strip cools to room temperature. Increase in the rolling velocity and subsequently the cooling rate affect thermal stresses. In this study a mathematical model for prediction of austenite- ferrite phase transition kinetics and thermo-mechanical stresses on the run-out table after hot rolling was developed for low carbon ferrite steels....
Simulation of Non-isothermal Austenite to Ferrite Transformation by Using Cellular Automaton Method
, M.Sc. Thesis Sharif University of Technology ; Serajzadeh, Siamak (Supervisor)
Abstract
In this study, transformation of austenite to ferrite under continuous cooling condition of a low carbon steel was investigated. In the first step, a heat transfer model was employedconsidering governing heat transfer boundary conditions and a microstructure model based on Cellular Automaton method was used simultaneouslyto predict austenite to ferrite transformation progress. The influence of pre-heating temperature and primary austenite grain size on the final ferrite grain size and distribution were perdected. To verify the simulation results, experimental processes were utilized. The microstructure distribution was determined by means of Clemex Pro software then, these results were...
, M.Sc. Thesis Sharif University of Technology ; Karimi Taheri, Ali (Supervisor)
Abstract
This study was conducted in order to investigate the effect of difference in electrical resistivity between low carbon steel and austenitic stainless steel on the physical and mechanical properties and fracture mode of dissimilar resistance spot welds of these alloys. For this purpose, plastic deformation using constrained groove pressing combined with rolling applied to low carbon steel in three levels of 40%, 156% and 272%. Microstructural characterization, micro-hardness measurements and shear-tension test were performed. It was shown that by increasing the pre-strain in low carbon steel its electrical resistivity increases from 13.08 μΩ.cm to 19.5 μΩ.cm and because of reduction of...
An Investigation Into the Energy Absorption of Severely Plastic Deformed Low Carbon Steel
, M.Sc. Thesis Sharif University of Technology ; Kazeminezhad, Mohsen (Supervisor)
Abstract
So far many investigations was performed in the field of energy absorption of mono and bi-layer sheets. As respects, severe plastic deformation process causes grain refinement and strength increase, there is not any study in feild of energy absorption of the severely plastic deformed sheets. The aim of this project was to investigate energy absorption of constrain groove pressed sheets by using different methods such as tensile test and wedge tear test. In this project, low carbon steel was processed by constrain groove press and mechanical properties of sheets was investigated, by using tensile test. It has been observed that ductility reduced and strength increased with increasing the...
, M.Sc. Thesis Sharif University of Technology ; Kazeminezhad, Mohsen (Supervisor) ; Kokabi, Amirhossein (Supervisor)
Abstract
Considering that automobile weigth reduction in industry is important, improvement the strength of low carbon steel sheets is important. These sheets can be supported the service condition in lower thicknesses. Bulk nano-structured materials have been mostly attracted in materials science due to their unique physical and mechanical properties. Severe plastic deformation (SPD) is one of the most efficient methods to produce ultra fine grained or nano-structured materials. Materials produced by SPD are of great importance because of (1) non-porous structure, (2) great mechanical properties such as high strength and toughness and (3) proper dimension for mechanical and physical testing. ...
Effect of Strain Path on Static Recrystallization Behavior of a Steel
, M.Sc. Thesis Sharif University of Technology ; Serajzadeh, Siamak (Supervisor)
Abstract
Static recrystllization in low carbon steel after two type of deformation –sidepress as an inhomogeneous deformation and rolling as a common industrial process - has been simulated using Cellular Automata (CA). The finite element method was utilized to compute the strain and stored energy distribution due to deformation. The initial microstructures were created by simulation of recrystallization with homogeneous site-saturated nucleation and topologic deformation was also considered in model. Subsequently using the result of FEM, stored energy of deformation was calculated and transferred into a two dimensional CA lattice. Nucleation rate and grain boundary velocity were considered...
Characterization of dynamic recrystallization parameters for a low carbon resulfurized free - cutting steel
, Article Materials and Design ; Vol. 53 , January , 2014 , pp. 910-914 ; ISSN: 02641275 ; Akbarzadeh, A ; Sharif University of Technology
Abstract
The hot working behavior of a low carbon resulfurized free-cutting steel was studied by hot compression tests at temperature range of 1000-1200°C with strain rates of 0.001 to 1s-1. The conventional parameters such as activation energy of deformation and relationships between flow stress/strain and Zener-Hollomon parameter were determined. Both the critical stress and strain for initiation of dynamic recrystallization (DRX) were determined using: (1) strain hardening rate versus stress curve, (2) the natural logarithm of strain hardening rate versus strain curve, and (3) the constitutive equations. In summary, for low carbon resulfurized free - cutting steels, the activation energy of...
3D finite element analysis and experimental validation of constrained groove pressing-cross route as an SPD process for sheet form metals
, Article International Journal of Advanced Manufacturing Technology ; Volume 73, Issue 9-12 , August , 2014 , Pages 1291-1305 ; ISSN: 02683768 ; Abbaszadeh, M ; Mohebpour, S. R ; Eskandari, H ; Sharif University of Technology
Abstract
A new modification of constrained groove pressing (CGP) process named as constrained groove pressing-cross route (CGP-CR) was suggested for severe plastic deformation (SPD) of sheet form metals with great potential for fabricating high strength nanostructured sheets. This process is based on the conventional CGP process including some modifications. One pass of this process includes eight stages (four corrugation and four flattening) and involves 90° cross-rotation between each two stages. As a result of each CGP-CR pass, a strain magnitude of ∼2.32 is imparted to the sample. To simulate the process, finite element modeling (FEM) was carried out using three-dimensional finite element...
Differential scanning calorimetry study of constrained groove pressed low carbon steel: Recovery, recrystallisation and ferrite to austenite phase transformation
, Article Materials Science and Technology (United Kingdom) ; Vol. 30, issue. 7 , 2014 , pp. 765-773 ; ISSN: 02670836 ; Kazeminezhad, M ; Sharif University of Technology
Abstract
Low carbon steel sheets are subjected to severe plastic deformation (SPD) via constrained groove pressing (CGP) up to five passes. As a result of this process, strain magnitude up to 5?8 is imposed to the sheets, which leads to grain size of 225 nm. These nanostructured steel sheets, due to their high dislocation density and ultrafine microstructure, are very sensitive to heating. In the present study, recovery, recrystallisation and ferrite to austenite phase transformation phenomena for the SPD steel are investigated using differential scanning calorimetry method. The results show that with increasing the strain in steel sheets, the deformed stored energy (released through recovery and...
On the failure behavior of highly cold worked low carbon steel resistance spot welds
, Article Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science ; Vol. 45, issue. 3 , Oct , 2014 , p. 1376-1389 ; 10735623 ; Kazeminezhad, M ; Kokabi, A. H ; Sharif University of Technology
Abstract
Highly cold worked (HCW) low carbon steel sheets with cellular structure in the range of 200 to 300 nm are fabricated via constrained groove pressing process. Joining of the sheets is carried out by resistance spot welding process at different welding currents and times. Thereafter, failure behavior of these welded samples during tensile-shear test is investigated. Considered concepts include; failure load, fusion zone size, failure mode, ultimate shear stress, failure absorbed energy, and fracture surface. The results show that HCW low carbon steel spot welds have higher failure peak load with respect to the as-received one at different welding currents and times. Also, current limits for...