Search for: annealing
Total 381 records
Article Materiali in Tehnologije ; Volume 51, Issue 1 , 2017 , Pages 173-177 ; 15802949 (ISSN) ; Kazeminezhad, M ; Sharif University of Technology
Institute of Metals Technology 2017
To study the grain-refinement ability of ultra-rapid annealing (URA), heating rates from 0.3 °C/s up to 1200 °C/s with conventional annealing and URA in the intercritical temperature range were performed on severely deformed low-carbon steel. The results show that recrystallization in conventional annealing is completed below the critical temperature of Ac1 without grain refinement. URA up to 730 °C at a heating rate of 200 °C/s causes grain refinement due to full interaction between the recrystallization and phase transformation. URAs up to 730 °C with heating rates of 600 °C/s and 1000 °C/s lead to partial grain refinement and no grain refinement, respectively. During annealing with a...
Computer simulation of the effect of post annealing parameters on the microstructure inhomogeneity of the non-uniformly deformed copper, Article Journal of Computer-Aided Materials Design ; Volume 13, Issue 1-3 , 2006 , Pages 221-232 ; 09281045 (ISSN) ; Karimi Taheri, A ; Tieu, A. K ; Sharif University of Technology
A computer simulation on the basis of the Finite Element Method and Monte Carlo Model is developed to simulate the microstructure of the non-uniformly deformed copper workpiece after annealing. Using the computer simulation, the effects of annealing time and temperature on the microstructure inhomogeneity of the workpiece are simulated and investigated quantitatively, by defining an Inhomogeneity Factor, to design an annealing program for reducing the microstructure inhomogeneity. The results show that with increasing the parameters of annealing time and temperature, the inhomogeneity is decreased when one of the parameters is constant. Also, at high annealing temperature, the annealing time...
Article Annals of Nuclear Energy ; Volume 29, Issue 1 , 2002 , Pages 41-51 ; 03064549 (ISSN) ; Setayeshi, S ; Salehi, A. A ; Sharif University of Technology
This paper presents a new method to solve the problem of finding the best configuration of fuel assemblies in a pressurized water reactor (PWR) core. Finding the optimum solution requires a huge amount of calculations in classical methods. It has been shown that the application of continuous Hopfield neural network accompanied by simulated annealing method to this problem not only reduces the amount of calculations, but also guarantees finding the best solution. In this study flattening of neutron flux inside the reactor core of Bushehr NPP is considered as the objective function. The result is the optimum configuration which is in agreement with the pattern proposed by the designer. © 2001...
Effect of intercritical annealing on retained austenite characterization in textured TRIP-assisted steel sheet, Article Materials Characterization ; Volume 57, Issue 4-5 , 2006 , Pages 408-413 ; 10445803 (ISSN) ; Akbarzadeh, A ; Daneshi, Gh ; Sharif University of Technology
Optimization of high strength and high formability of multiphase cold rolled sheet TRIP-aided steels is based on the composition and the austempering conditions. The effect of intercritical annealing temperature on the volume fraction and carbon concentration of the retained austenite was investigated in two different TRIP-aided steels. Experimental results show that the optimum annealing temperatures are 860 °C for Al-containing and 810 °C for Si-containing TRIP steels. It was demonstrated that the measurement of retained austenite can be successfully performed for textured TRIP steels by XRD. © 2006 Elsevier Inc. All rights reserved
Application of the simplex simulated annealing technique to nonlinear parameter optimization for the SAFT-VR equation of state, Article Chemical Engineering Science ; Volume 60, Issue 23 , 2005 , Pages 6607-6621 ; 00092509 (ISSN) ; Ghotbi, C ; Galindo, A ; Sharif University of Technology
Elsevier Ltd 2005
A non-equilibrium simplex simulated annealing algorithm is applied as a global optimization method to parameter optimization for an equation of state based on the generalized statistical associating fluid theory incorporating potentials of variable range. The parameters are determined by optimizing the calculated phase behaviour of a number of pure solvents, such as water and alcohols, and aqueous electrolyte solutions. The optimized parameters obtained via the simulated annealing algorithm are compared to those obtained using the simplex method and, for the electrolyte solutions, a gradient-based quasi-Newton method. In the case of the pure solvents, the lowest values of the objective...
Article American Journal of Operations Research ; Vol.2 No.3, September 2012, 391-398 ; Eshghi, Kourosh ; Shokri Razaghi, Hooshmand ; Sharif University of Technology
Scheduling sports leagues has drawn significant attention to itself in recent years, as it involves considerable revenue as well as challenging combinatorial optimization problems. A particular class of these problems is the Traveling Tournament Problem (TTP) which focuses on minimizing the total traveling distance for teams. In this paper, an efficient simulated annealing approach is presented for TTP which applies two simultaneous and disparate models for the problem in order to search the solutions space more effectively. Also, a computationally efficient modified greedy scheme is proposed for constructing a favorable initial solution for the simulated annealing algorithm. Our...
Article International Journal of Operational Research (IJOR) ; Volume 11, Number 2/2011 Pages 136-159 ; Eshghi, Kourosh ; Sharif University of Technology
The graph colouring problem, as an important NP-complete problem, is considered in this paper and a hybrid meta-heuristic approach is developed to solve it. The initial solution of the algorithm, generated by a heuristic method, is used by a simulated annealing (SA) approach to generate new solutions until no progress in a number of solutions reported. At this stage, the algorithm will use a tabu search routine and this local search operator will be followed for some iterations. After finding a better solution, the algorithm is again followed through SA. Efficiency of the algorithm is showed through various experiments on well-known benchmark problems of DIMACS. Comparison with the available...
Effects of post-annealing on the microstructure and mechanical properties of friction stir processed Al–Mg–TiO2 nanocomposites [electronic resource], Article Journal of Materials & Design ; November 2014, Volume 63, Pages 30–41 ; Simchi, A. (Abdolreza) ; Kokabi, A. H ; Gerlich, A. P ; Nosko, M ; Sharif University of Technology
Aluminum matrix nanocomposites were fabricated via friction stir processing of an Al–Mg alloy with pre-inserted TiO2 nanoparticles at different volume fractions of 3%, 5% and 6%. The nanocomposites were annealed at 300–500 °C for 1–5 h in air to study the effect of annealing on the microstructural changes and mechanical properties. Microstructural studies by scanning and transmission electron microscopy showed that new phases were formed during friction stir processing due to chemical reactions at the interface of TiO2 with the aluminum matrix alloy. Reactive annealing completed the solid-state reactions, which led to a significant improvement in the ductility of the nanocomposites (more...
Simulation of static recrystallization in non-isothermal annealing using a coupled cellular automata and finite element model, Article Computational Materials Science ; Volume 53, Issue 1 , 2012 , Pages 145-152 ; 09270256 (ISSN) ; Serajzadeh, S ; Sharif University of Technology
A coupled cellular automata and finite element model has been proposed to evaluate static recrystallization kinetics during non-isothermal annealing of cold deformed low carbon steels. The effects of various factors including heating rate, annealing temperature, and initial microstructures have been considered in the model to accurately predict the static recrystallization kinetics and the final microstructures. In order to examine the employed algorithm, the predicted results have been compared with the experimental observations and a good agreement was found between the two sets of results
Article Metals and Materials International ; Volume 23, Issue 5 , 2017 , Pages 984-993 ; 15989623 (ISSN) ; Kazeminezhad, M ; Sharif University of Technology
A low-carbon steel sheet containing 0.05 C, 0.203 Mn, and 0.0229 Si (all in wt%) was rapidly annealed in a temperature range of 300 °C to 600 °C after severe plastic deformation by using constrained groove pressing (CGP) technique. Microstructure evolution was investigated by scanning electron and optical microscopes. Mechanical properties were evaluated by hardness measurements and shear punch test. The results showed a thermal stability up to 400 °C where recrystallization did not occur in the specimens even after 7200 s. This thermal stability is in agreement with previously reported results of conventional annealing of the same steel after CGP. However, annealing at 500 °C and 600 °C led...
Article Proceedings of 2003 IEEE Conference on Control Applications, Istanbul, 23 June 2003 through 25 June 2003 ; Volume 1 , 2003 , Pages 664-668 ; Borujeni, B. S ; Sharif University of Technology
A novel Locomotion and gait planning method for a surface walking/climbing robot based on sequential 4-bar mechanism motions is presented. The robot moves on a surface through decoupled transverse gaits and turning gaits with desired length and angle. For implementation of turning gaits three methods of Simulated Annealing Accurate Planning (SAAP), Gradient Based Planning (GBP) and Hybrid Accurate Planning (HAP) are studied. Where the last method was found the most effective approach
Article IEEE Transactions on Nuclear Science ; Volume 49 IV, Issue 3 , 2002 , Pages 1574-1578 ; 00189499 (ISSN) ; Setayeshi, S ; Salehi, A. A ; Sharif University of Technology
The Hopfield network is studied from the standpoint of taking it as a computational model in optimizing the fuel management of pressurized water reactors (PWRs). In this paper, the flattening of the neutron flux is considered as the objective function. By this consideration, the power peaking inside the reactor core is also minimized. Regarding the local minimum problem of Hopfield network, the simulated annealing method is applied to improve the Hopfield solution. The method is applied to Bushehr Nuclear Power Plant (PWR design) and the result is compared with the core configuration purposed by the designer
Effect of cold rolling reduction and intercritical annealing temperature on the bulk texture of two TRIP-aided steel sheets, Article Journal of Materials Processing Technology ; Volume 203, Issue 1-3 , 2008 , Pages 293-300 ; 09240136 (ISSN) ; Akbarzadeh, A ; Daneshi, Gh ; Sharif University of Technology
High strength TRIP-aided steel sheets with high formability and better ductility are of industrial interest. Texture control and retained austenite characterization are considered as the main factors with respect to the formability and ductility. Processing parameter such as initial conditions of hot rolling, cold rolling to final size of sheet, intercritical annealing after cold rolling and subsequent isothermal heat treatment to achieve TRIP specification in product, affect bulk texture of sheets. Moreover, chemical composition of steel should be noted especially because it can change the intensity of orientation and final macro texture of sheet. In this work, the effect of cold rolling...
The effect of Si addition and Ta diffusion barrier on growth and thermal stability of NiSi nanolayer, Article Microelectronic Engineering ; Volume 85, Issue 3 , 2008 , Pages 548-552 ; 01679317 (ISSN) ; Akhavan, O ; Moshfegh, A. Z ; Sharif University of Technology
Formation and thermal stability of nanothickness NiSi layer in Ni(Pt 4 at.%)/Si(1 0 0) and Ni0.6Si0.4(Pt 4 at.%)/Si(1 0 0) structures have been investigated using magnetron co-sputtering deposition method. Moreover, to study the effect of Si substrate in formation of NiSi and its thermal stability, we have used Ta diffusion barrier between the Ni0.6Si0.4 layer and the Si substrate. Post annealing treatment of the samples was performed in an N2 environment in a temperature range from 200 to 900 °C for 2 min. The samples were analyzed by four point probe sheet resistance (Rs) measurement, X-ray diffraction (XRD) and atomic force microscopy (AFM) techniques. It was found that the annealing...
Article Materials Science and Engineering A ; Volume 447, Issue 1-2 , 2007 , Pages 174-179 ; 09215093 (ISSN) ; Akbarzadeh, A ; Daneshi, G. H ; Sharif University of Technology
In developed multiphase high strength, high formability TRIP-aided steel, Luders bands are observed similar to conventional low carbon steels. Retained austenite as the most effective constituent in TRIP steels, is responsible for Luders band formation as well as other properties such as formability, physical and mechanical properties. In the present study, a correlation between the Luders strain and the retained austenite characterization is proposed and verified by experimental evidences of the work carried out on two types of TRIP steel sheets. Intercritical annealing of cold rolled TRIP steels at different temperatures change the volume fraction of the retained austenite as well as the...
Article Materials and Design ; Volume 26, Issue 1 , 2005 , Pages 89-93 ; 02613069 (ISSN) ; Mousavi, S ; Sharif University of Technology
Elsevier Ltd 2005
Impact and tensile strength of polystyrene and nylon 6 samples, which have been produced by injection molding before and after annealing in different conditions are obtained. Polystyrene samples that are heated on vacuum conditions can deform highly even in temperatures much less than polystyrene glass temperature. This phenomenon is reduced significantly by heating samples to annealing temperature in atmospheric pressure and then removing air from sample environment in constant temperature. Deformation problems for nylon were not so important but due to high temperature implied for annealing of nylon parts, some color change due to oxidative degradation are observed. So for nylon parts a...
Article Materials and Design ; Volume 44 , 2013 , Pages 487-492 ; 02641275 (ISSN) ; Kokabi, A. H ; Seyed Reihani, S. M ; Cheng, W. J ; Wang, C. J ; Sharif University of Technology
In this work, the effects of the annealing temperature and duration on the joint strength of the steel/aluminum lap joints made by friction stir welding were investigated. The strength of the welded joints was evaluated by shear-tensile test. Formation of intermetallic layer at the joint interface and the fracture locations were studied using scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS) and electron backscatter diffraction (EBSD). The results indicated that longer time of annealing treatment resulted in higher joint strength at 300 and 350 °C and that the rate of the increase in joint strength with time was about 72% higher at the latter temperature...
Article Multidiscipline Modeling in Materials and Structures ; Volume 11, Issue 1 , 2015 , Pages 88-101 ; 15736105 (ISSN) ; Serajzadeh, S ; Sharif University of Technology
Emerald Group Publishing Ltd 2015
Purpose - The purpose of this paper is to study the kinetics of static recovery in cold-rolled aluminum alloy under different heating rates. Design/methodology/approach - Deformation modeling was first performed to assess the distributions of plastic strain and stress within the deformed alloy. In the next stage, thermal analysis and the rate equation of static recovery were employed to determine the progress of static recovery under non-isothermal conditions. Accordingly, a thermal finite element analysis and the Runge-Kutta method were utilized to handle the transient heat conduction and the progress of static recovery. Finally, low temperature annealing heat treatments were conducted to...
Article Journal of Solid State Electrochemistry ; Vol. 19, Issue. 1 , 2014 , pp. 269-274 ; ISSN: 1432-8488 ; Zad, A. I ; Shahrokhian, S ; Sharif University of Technology
Here, a solvothermal method for synthesis of porous Ni–Co binary oxide (NiCo2O4) nanorods followed by thermal decomposition is described. The prepared nanorods were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunauer Emmett Teller (BET) methods. These porous NiCo2O4 nanostructures were promising candidates in the development of high capacity supercapacitors and having excellent cycling performance due to high specific surface area. In addition, the influence of annealing rate on the structure and electrochemical behavior of the synthesized nanorods was investigated. The results showed that the annealing rate had a direct effect on the crystalline...
Article EMS 2009 - UKSim 3rd European Modelling Symposium on Computer Modelling and Simulation, 25 November 2009 through 27 November 2009, Athens ; 2009 , Pages 87-91 ; 9780769538860 (ISBN) ; Mohamadi, H ; Saniee Abadeh, M ; Foroughifar, A ; Sharif University of Technology
In this paper, a novel classification approach is presented. This approach uses fuzzy if-then rules for classification task and employs a hybrid optimization method to improve the accuracy and comprehensibility of obtained outcome. The mentioned optimization method has been formulated by simulated annealing and genetic algorithm. In fact, the genetic operators have been used as perturb functions at the core of simulated annealing heuristic. Results of proposed approach have been compared with several well-known methods such as Naïve Bayes, Support Vector Machine, Decision Tree, k-NN, and GBML, and show that our method performs the classification task as well as other famous algorithms. ©...