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The effect of carbon on the restoration phenomena during hot deformation of carbon steels
, Article Zeitschrift fuer Metallkunde/Materials Research and Advanced Techniques ; Volume 94, Issue 8 , 2003 , Pages 916-921 ; 00443093 (ISSN) ; Karimi Taheri, A ; Zebarjad, S. M ; Sharif University of Technology
Carl Hanser Verlag
2003
Abstract
A study has been made to determine the influence of the carbon content on the kinetics of dynamic and static recrystallization during and after hot deformation of carbon steels. For this purpose, single- and double-hit hot compression experiments at various strain rates and temperatures together with the Avrami-type kinetics equation and Bergstrom approach have been utilized to investigate recrystallization behavior. The results show that the apparent activation energy of hot deformation decreases with increasing carbon content and this phenomenon results in a faster dynamic recrystallization at high temperatures and/or low strain rates. Also, increasing carbon content leads to a higher rate...
An investigation of the silicon role on austenite recrystallization
, Article Materials Letters ; Volume 56, Issue 6 , 2002 , Pages 984-989 ; 0167577X (ISSN) ; Karimi Taheri, A ; Sharif University of Technology
2002
Abstract
The role of silicon on austenite recrystallization was investigated using hot compression experiments on a low carbon and a high silicon steel samples. The models were proposed to describe the hot deformation behavior of metals regarding dynamic recovery. The rate of static recrystallization was found lower in the silicon steel in comparison with low carbon steel. Silicon was found to produce a lower rate of dynamic recovery due to its effect on the austenite staking fault energy
An investigation into the effect of carbon on the kinetics of dynamic restoration and flow behavior of carbon steels
, Article Mechanics of Materials ; Volume 35, Issue 7 , 2003 , Pages 653-660 ; 01676636 (ISSN) ; Taheri, A. K ; Sharif University of Technology
2003
Abstract
A study has been made to determine the influence of the carbon content on the kinetics of dynamic recrystallization and recovery as well as flow stress during hot deformation of carbon steels. For this purpose, single hit hot compression experiments at various strain rates and temperatures on two grades of carbon steel together with the Avrami-type kinetics equation and Bergstrom approach have been utilized. The results show that the apparent hot deformation activation energy decreases with increasing carbon content and this phenomenon results in a faster dynamic recrystallization and recovery and a lower flow stress at high temperatures and/or low strain rates in high carbon steels, while...
Hot deformation behavior of P/M Al6061-20% SiC composite
, Article 2006 Powder Metallurgy World Congress and Exhibition, PM 2006, Busan, 24 September 2006 through 28 September 2006 ; Volume 534-536, Issue PART 2 , 2007 , Pages 897-900 ; 02555476 (ISSN); 0878494197 (ISBN); 9780878494194 (ISBN) ; Simchi, A
Trans Tech Publications Ltd
2007
Abstract
In the present work, hot workability of particulate-reinforced Al6061-20%SiC composite produced by direct hot extrusion technique was studied. Uniaxial hot compression test at various temperatures and strain rates was used and the workability behavior was evaluated from the flow curves and the attendant microstructures. It was shown that the presence of SiC particles in the soft Al6061 matrix deteriorates the hot workability. Bulging of the specimens and flow lines were observed, which indicates the plastic instability during hot working. Microstructure of the composites after hot deformation was found to be heterogeneous, i.e. the reinforcement clusters were observed at the flow lines. The...
The effect of carbon on the restoration phenomena during hot deformation of carbon steels
, Article International Journal of Materials Research ; Volume 94, Issue 8 , 2022 , Pages 916-921 ; 18625282 (ISSN) ; Karimi Taheri, A ; Zebarjad, S. M ; Sharif University of Technology
Walter de Gruyter GmbH
2022
Abstract
A study has been made to determine the influence of the carbon content on the kinetics of dynamic and static recrystallization during and after hot deformation of carbon steels. For this purpose, single- and double-hit hot compression experiments at various strain rates and temperatures together with the Avrami-type kinetics equation and Bergstrom approach have been utilized to investigate recrystallization behavior. The results show that the apparent activation energy of hot deformation decreases with increasing carbon content and this phenomenon results in a faster dynamic recrystallization at high temperatures and/or low strain rates. Also, increasing carbon content leads to a higher rate...
Hot deformation behavior of Fe-29Ni-17Co alloy
, Article Transactions of Nonferrous Metals Society of China (English Edition) ; Volume 23, Issue 11 , 2013 , Pages 3271-3279 ; 10036326 (ISSN) ; Abbasi, S. M ; Taheri, A. K ; Momeni, A ; Sharif University of Technology
2013
Abstract
Hot compression tests were carried out on a Fe-29Ni-17Co alloy in the temperature range of 900 °C to 1200 °C and at strain rates of 0.001-1 s-1. Dynamic recrystallization was found responsible for flow softening during hot compression. The flow behavior was successfully analyzed by the hyperbolic sine equation and the corresponding material constants A, n and α were determined. The value of apparent activation energy was determined as 423 kJ/mol. The peak and steady state strains showed simple power-law dependence on the Zener-Hollomon parameter. The dynamic recrystallization kinetics was analyzed using Avrami equation and the corresponding exponent was determined to be about 2.7. This...
On the constitutive modeling and microstructural evolution of hot compressed A286 iron-base superalloy
, Article Journal of Alloys and Compounds ; Volume 564 , 2013 , Pages 13-19 ; 09258388 (ISSN) ; Abbasi, S. M ; Momeni, A ; Karimi Taheri, A ; Sharif University of Technology
2013
Abstract
The hot working behavior of A286 was studied using hot compression tests over temperature range of 950-1100 °C and at strain rates of 0.001-1 s -1. The flow curves of the material over the studied temperatures and strain rates were typical of dynamic recrystallization. However, some points reflected a change in the mechanism of softening with the change of strain rate. The relation between flow stress, deformation temperature and strain rate was examined via power-law, hyperbolic sine and exponential constitutive equations and the hyperbolic sine function was found more appropriate. The peak strain increased with strain rate up to 0.01 s-1 and then unexpectedly decreased at higher strain...
The effect of deformation heating on restoration and constitutive equation of a wrought equiatomic NiTi alloy
, Article Journal of Materials Engineering and Performance ; Volume 21, Issue 4 , April , 2012 , Pages 516-523 ; 10599495 (ISSN) ; Karimi Taheri, A ; Karimi Taheri, K ; Sarraf, I. S ; Abbasi, S. M ; Sharif University of Technology
Abstract
In this study, a set of constitutive equation corrected for deformation heating is proposed for a near equiatomic NiTi shape memory alloy using isothermal hot compression tests in temperature range of 700 to 1000 °C and strain rate of 0.001 to 1 s -1. In order to determine the temperature rise due to deformation heating, Abaqus simulation was employed and varied thermal properties were considered in the simulation. The results of hot compression tests showed that at low pre-set temperatures and high strain rates the flow curves exhibit a softening, while after correction of deformation heating the softening is vanished. Using the corrected flow curves, the power-law constitutive equation of...
Hot deformation behavior of hot extruded Al-6Mg alloy
, Article Materials Science and Engineering A ; Volume 535 , February , 2012 , Pages 216-221 ; 09215093 (ISSN) ; Kazeminezhad, M ; Sharif University of Technology
Abstract
The behavior of hot extruded Al-6Mg during hot deformation has been studied using hot compression test. The tests were performed at temperatures of 350, 450, and 550°C and strain rates of 0.001, 0.1, and 1s -1. Due to the effects of friction and adiabatic heating generated during compression, the attained true stress-true strain curves have been corrected. After correction of friction effect, the virtual work hardening has been removed from stress-strain curves. The flow stress increases and reaches a steady state after correction of adiabatic heating effect. Corrected curves and microstructural examinations exhibit the occurrence of dynamic recovery during hot compression of the alloy. The...
Evaluation of low strain rate constitutive equation of 7075 aluminium alloy at high temperature
, Article Materials Science and Technology ; Volume 27, Issue 6 , 2011 , Pages 1067-1072 ; 02670836 (ISSN) ; Karimi Taheri, A ; Sharif University of Technology
2011
Abstract
The 7075 aluminium alloy is one of the most important engineering alloys utilised extensively in aircraft and transportation industries due to its high specific strength. In the present research, the flow behaviour of this alloy has been investigated using hot compression test at strain rates of 0.001, 0.01, 0.1 and 1 s-1 and temperatures of 350, 400 and 450°C. The results reveal that dynamic softening occurred in these temperatures and strain rates. The activation energy, strain rate sensitivity and two constitutive equations (hyperbolic sine law and the power law) are derived from the results. It is shown that the hyperbolic sine law has a better agreement with the experimental results
An investigation into the deformation behaviour of AA6061-5% SiC p composite during and after hot extrusion process
, Article Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications ; Volume 225, Issue 1 , 2011 , Pages 22-31 ; 14644207 (ISSN) ; Mirjalili, A ; Serajzadeh, S ; Sharif University of Technology
Abstract
In this study, hot extrusion of AA6061-5% SiCp composite was studied to determine the composite thermo-mechanical behaviour during deformation and the mechanical properties of extruded composite. Hot compression tests were first carried out to obtain the flow stress behaviour of the composite at different temperatures and strain rates. Then a mathematical model was used to estimate the required energy as well as to predict temperature and strain distributions during the process. Finally, hot extrusion experiments were performed in order to verify the predictions and, also, tensile and hardness testing were conducted to evaluate mechanical properties of extruded material. Comparison between...
The prediction of hot flow behavior of Al-6%Mg alloy
, Article Mechanics Research Communications ; Volume 36, Issue 2 , 2009 , Pages 252-259 ; 00936413 (ISSN) ; Karimi Taheri, A ; Sharif University of Technology
2009
Abstract
In this research, the plastic flow behavior of Al-6%Mg alloy was studied by analyzing the results of hot compression tests in a range of temperature and strain rate. Then, an artificial neural network (ANN) model was trained at which the temperature, strain-rate, and strain parameters were used as the input layer and the flow stress as the output. The comparison of the predicted and experimental results of stress-strain curve proved the prediction capability of the ANN model. © 2008 Elsevier Ltd. All rights reserved
High temperature deformation and processing map of a NiTi intermetallic alloy
, Article Intermetallics ; Volume 19, Issue 10 , October , 2011 , Pages 1399-1404 ; 09669795 (ISSN) ; Aboutalebi, M ; Kheirandish, S ; Karimi Taheri, A ; Abbasi, S. M ; Sharif University of Technology
2011
Abstract
The deformation behavior of a 49.8 Ni-50.2 Ti (at pct) alloy was investigated using the hot compression test in the temperature range of 700 °C-1100 °C, and strain rate of 0.001 s-1 to 1 s-1. The hot tensile test of the alloy was also considered to assist explaining the related deformation mechanism within the same temperature range and the strain rate of 0.1 s-1. The processing map of the alloy was developed to evaluate the efficiency of hot deformation and to identify the instability regions of the flow. The peak efficiency of 24-28% was achieved at temperature range of 900 °C-1000 °C, and strain rates higher than 0.01 s -1 in the processing map. The hot ductility and the deformation...
A study on the hot workability of wrought NiTi shape memory alloy
, Article Materials Science and Engineering A ; Volume 528, Issue 18 , July , 2011 , Pages 5656-5663 ; 09215093 (ISSN) ; Kheirandish, S ; Aboutalebi, M ; Taheri, A. K ; Abbasi, S. M ; Sharif University of Technology
2011
Abstract
The hot workability of a wrought 49.8 Ni-50.2 Ti (at pct) alloy was assessed using the hot compression tests in temperature range of 700-1000°C, strain rate of 0.001-1s-1, and the total strain of 0.7. The constitutive equations of Arrhenius-type hyperbolic-sine function was used to describe the flow stress as a function of strain rate and temperature. The preferable regions for hot workability of the alloy were achieved at Z (Zener-Holloman parameter) values of about 109-1013 corresponding to the peak efficiency of 20-30% in the processing map. However, a narrow area in the processing map including the deformation temperature of 1000°C and strain rate of 1s-1 is inconsistent with the related...
The effect of Cu addition on the hot deformation behavior of NiTi shape memory alloys
, Article Journal of Alloys and Compounds ; Volume 499, Issue 1 , June , 2010 , Pages 57-62 ; 09258388 (ISSN) ; Kheirandish, Sh ; Aboutalebi, M ; Karimi Taheri, A ; Abbasi, S. M ; Sharif University of Technology
2010
Abstract
The influence of Cu addition on the hot deformation behavior of NiTi shape memory alloys was investigated using hot compression test. A series of alloys with different Cu contents of Ti50.4Ni49.6-xCux (x = 0, 3, 5, 7 at.%) were deformed under compression to a true strain of 0.7 at the temperature range of 700-1000 °C with 100 °C intervals and constant strain rate of 0.1 s-1. The stress-strain curves showed that the addition of Cu to NiTi alloy made the flow curves shift upward. This was confirmed by the calculated critical stress, σc, obtained from inflections in θ-σ plots, which is attributed to the formation of high strength Cu containing precipitates and solid solution hardening caused by...