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Grain size distribution after similar and dissimilar gas tungsten arc welding of a ferritic stainless steel
, Article Journal of Mining and Metallurgy, Section B: Metallurgy ; Volume 51, Issue 1 , 2015 , Pages 61-66 ; 14505339 (ISSN) ; Serajzadeh, S ; Kokabi, A. H ; Fischer, A ; Sharif University of Technology
Technical Faculty in Bor
2015
Abstract
In this study, gas tungsten arc welding of ferritic stainless steel and grain size distribution in heat affected zone of the welded samples were investigated. Both similar and dissimilar arc welding operations were considered where in dissimilar welding joining of stainless steel to mild steel was examined. In the first stage, a three-dimensional model was developed to evaluate temperature field during and after arc welding while the model was performed using finite element software, ANSYS. Then, the effects of welding heat input and dissimilarity of the joint on the weld pool shape and grain growth in HAZ of stainless steel was investigated by means of model predictions and experimental...
Improvement in Mechanical Properties of Microalloyed Steel 30MSV6 by a Precipitation Hardening Process
, Article Journal of Iron and Steel Research International ; Volume 20, Issue 5 , 2013 , Pages 66-73 ; 1006706X (ISSN) ; Nategh, S ; Yoozbashizadeh, H ; Ekrami, A ; Sharif University of Technology
2013
Abstract
The microstructural evolutions and mechanical properties of vanadium microalloyed steel (30MSV6) during precipitation hardening were studied. The effects of aging temperature and cooling rate on mechanical strength (yield strength and ultimate tensile strength) were similar. Increasing aging temperature or cooling rate firstly increased the mechanical strength of specimens up to their maximum values, which then decreased with further increase in aging temperature or cooling rate. Microstructural evolutions revealed that cooling rate had significant effects on the pearlite interlamellar spacing and size of pre-eutectoid ferrite. Unlike the effect of austenitizing temperature, the pearlite...
Modelling of the effect of operational parameters and concentration of some corrosion inhibitors on the corrosion of carbon steel
, Article Anti-Corrosion Methods and Materials ; Volume 49, Issue 6 , 2002 , Pages 426-432 ; 00035599 (ISSN) ; Kazemeini, M ; Safekordi, A ; Badakhshan, A ; Sharif University of Technology
2002
Abstract
Several corrosion inhibitors, such as, HEDP, sodium molybdate and zinc ions, were added to an aqueous corrosive media containing different concentrations chloride ions, and the corrosion rates (CRs) of carbon steel were measured at various temperatures. It was shown that, in the presence of more than 1,200 ppm of chloride ions, and temperatures greater than or equal to 42.5°C, the combination of HEDP, molybdate and zinc could not control the corrosion in a cooling water system. Then four different models were designed to represent the CR of carbon steel in presence of various corrosive parameters
The role of microstructure in mechanical behaviors of low-alloy sintered steels
, Article Scientia Iranica ; Volume 7, Issue 1 , 2000 , Pages 41-49 ; 10263098 (ISSN) ; Simchi, A ; Moradkhani, D ; Ashtari, M ; Khorsand, H ; Davami, P ; Sharif University of Technology
Sharif University of Technology
2000
Abstract
In this study, microstructural aspects that control fracture and deformation resistance of P/M materials are evaluated. Several low-alloy steels were produced under both experimental and commercial conditions for achieving different matrix phases and porosity levels with varying shape factors. A 'porosity map' was constructed and used for a quantified study of the dominant mechanism controlling mechanical behaviors. The role of inclusion gathering and secondary pores, as well as sintering mechanism and alloying method is considered and discussed. The mechanism assessment was performed by using microstructure examination through optical and scanning electron microscopy. The results...
Parametric Study of Concrete Connection Retrofitted by Steel Jacketing
, M.Sc. Thesis Sharif University of Technology ; Mofid, Massoud (Supervisor)
Abstract
This study investigates the cyclic experimental behavior of damaged exterior reinforced concrete beam–column joint specimens retrofitted with the proposed technique using steel elements called steel prop and curb. The technique is usable for local and global strengthening of reinforced concrete frames. Four half-scale RC joints were tested under the cyclic loading; two control specimens with the different beam heights were loaded up to their ultimate strength and this was followed by retrofitting of these damaged specimens as new specimens and tested again under the same loading system. This study indicate the importance of some parameters such as friction , jacket place , thickness of plate...
Laser welding of NiTi shape memory alloy: Comparison of the similar and dissimilar joints to AISI 304 stainless steel [electronic resource]
, Article Optics and Laser Technology ; Volume 54, 2013, Pages 151–158 ; Saatchi, A ; Kermanpur, A ; Sadrnezhaad, K ; Sharif Univercity of Technology
Abstract
The unique properties of NiTi alloy, such as its shape memory effect, super-elasticity and biocompatibility, make it ideal material for various applications such as aerospace, micro-electronics and medical device. In order to meet the requirement of increasing applications, great attention has been given to joining of this material to itself and to other materials during past few years. Laser welding has been known as a suitable joining technique for NiTi shape memory alloy. Hence, in this work, a comparative study on laser welding of NiTi wire to itself and to AISI 304 austenitic stainless steel wire has been made. Microstructures, mechanical properties and fracture morphologies of the...
Effect of current frequency on coating properties formed on aluminised steel by plasma electrolytic oxidation
, Article Surface Engineering ; Vol. 30, issue. 3 , 2014 , pp. 224-228 ; ISSN: 02670844 ; Faghihi Sani, M. A ; Rafizadeh, E ; Sharif University of Technology
Abstract
In the present study, plasma electrolytic oxidation process was carried out on aluminised steel with a pulsed bipolar electrical source at different frequencies, namely, 50, 300, 600 and 1500 Hz with constant 50% duty cycle for 10 min in an alkaline silicate electrolyte. Morphology, wear behaviour and corrosion resistance of the coatings were investigated by scanning electron microscopy, pin on disc and potentiodynamic polarisation experiment in 3·5 wt-%NaCl solution. The results showed that with increasing the pulse frequency, the density of the residual pores increases, but their size as well as the coating thickness decreases. The corrosion current density of the coating processed at 1500...
Modeling the correlation between heat treatment, chemical composition and bainite fraction of pipeline steels by means of artificial neural networks
, Article Neural Network World ; Volume 23, Issue 4 , 2013 , Pages 351-367 ; 12100552 (ISSN) ; Pouraliakbar, H ; Mamaghani, K. R ; Khalaj, M. J ; Sharif University of Technology
2013
Abstract
In the present study, bainite fraction results of continuous cooling of high strength low alloy steels have been modeled by artificial neural networks. The artificial neural network models were constructed by 16 input parameters including chemical compositions (C, Mn, Nb, Mo, Ti, N, Cu, P, S, Si, Al, V), Nb in solution, austenitizing temperature, initial austenite grain size and cooling rate over the temperature range of the occurrence of phase transformations. The value for the output layer was the bainite fraction. According to the input parameters in feed-forward back-propagation algorithm, the constructed networks were trained, validated and tested. To make a decision on the completion...
Microstructure and failure behavior of dissimilar resistance spot welds between low carbon galvanized and austenitic stainless steels
, Article Materials Science and Engineering A ; Volume 480, Issue 1-2 , 2008 , Pages 175-180 ; 09215093 (ISSN) ; Pouranvari, M ; Amirabdollahian, S ; Abedi, A ; Goodarzi, M ; Sharif University of Technology
2008
Abstract
Resistance spot welding was used to join austenitic stainless steel and galvanized low carbon steel. The relationship between failure mode and weld fusion zone characteristics (size and microstructure) was studied. It was found that spot weld strength in the pullout failure mode is controlled by the strength and fusion zone size of the galvanized steel side. The hardness of the fusion zone which is governed by the dilution between two base metals, and fusion zone size of galvanized carbon steel side are dominant factors in determining the failure mode. © 2007 Elsevier B.V. All rights reserved
Prediction of ferrite grain size and tensile properties of a low carbon steel
, Article Materials Science and Technology ; Volume 20, Issue 1 , 2004 , Pages 106-110 ; 02670836 (ISSN) ; Karimi Taheri, A ; Sharif University of Technology
Maney Publishing
2004
Abstract
A relationship between ferrite grain size, cooling rate from austenitising temperature, austenitising time, and austenitising temperature is developed to predict the ferrite grain size of a low carbon steel. The coefficients of that relationship are determined experimentally. A Hall-Petch relationship is used to predict the yield stress and fracture stress from the predicted ferrite grain size. Considering the experimental results, maximum errors of 12-5% and 6·5% were found in the prediction of ferrite grain size and strengths, respectively
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...
Axial fatigue behavior of MoNiCu alloyed sintered steel
, Article Proceedings of the 3rd International Powder Metallurgy Conference, Ankara, 4 September 2002 through 8 September 2002 ; 2002 , Pages 398-407 ; 9759246309 (ISBN) ; Janghorban, K ; Khorsand, H ; Yoozbashizade, H ; Jahromi, S. A. J ; Sharif University of Technology
2002
Abstract
In recent years, PM steel parts have been used due to materials saving and cost. Mechanical properties of PM parts made of Ultrapac-LA (Fe-.5Mo-1.5Cu-1. 75Ni) with 0.2 and 0.5% graphite addition have been studied. The chemical composition of Ultrapac-LA is similar to Distaloy AB. Specimens with dimensions of 89×6×5.5 mm were prepared. The green compacts were sintered at 1120°C in a 75 H2 -25 N2 atmosphere for 40 minutes to densities in the range of 6.7g/cm3 to 7 g/cm3. They were tested in static and cyclic loading, and their microstructures were studied by optical microscopy. Results show that porosity has a definite effect on fatigue resistance of this alloy. The formation of bainite and...
The role of heat treatment on wear behavior of powder metallurgy low alloy steels
, Article Materials and Design ; Volume 23, Issue 7 , 2002 , Pages 667-670 ; 02641275 (ISSN) ; Habibi, S. M ; Yoozbashizadea, H ; Janghorban, K ; Reihani, S. M. S ; Rahmani Seraji, H ; Ashtari, M ; Sharif University of Technology
Elsevier Ltd
2002
Abstract
The influence of manufacturing parameters such as compacting pressure, heat treatment and microstructure on the static and dynamic properties of Fe-1.75 Ni-1.5 Cu-0.5 Mo-0.6 C was investigated. Wear and fatigue tests were carried out on reciprocate wearing and tension compression mode, respectively. The results show that delamination wear mechanism of sintered steel is similar to that of conventional wrought or cast materials. But, in sintered material, open porosity acts as sites of generation and collection of wear debris or formation of subsurface cracks. Wear rate is decreased and fatigue strength is increased by heat treatment. © 2002 Elsevier Science Ltd. All rights reserved
On the analytical model of beam-to-column semi-rigid connections, using plate theory
, Article Thin-Walled Structures ; Volume 39, Issue 4 , 2001 , Pages 307-325 ; 02638231 (ISSN) ; Ghorbani Asl, M ; McCabe, S. L ; Sharif University of Technology
2001
Abstract
An analytical method is presented that can be used to determine the behavior of a particular steel beam-to-column extended end plate connection, in both linear and non-linear regions. This article demonstrates a closed form solution of the equations of deformation, for this type of connection. Besides, a step-by-step analytical procedure for establishment of the linear part of M-θ curve of this form of connection is developed. However, this technique can properly be extended to the non-linear regions, which is not considered in this article. The correctness of the results has been ascertained by a comparison, using non-linear finite element models as well as experimental approach; and very...
Predictions of toughness and hardness by using chemical composition and tensile properties in microalloyed line pipe steels
, Article Neural Computing and Applications ; 2014 ; Khalaj, G ; Pouraliakbar, H ; Jandaghi, M. R ; Sharif University of Technology
Abstract
Artificial neural networks with multilayer feed forward topology and back propagation algorithm containing two hidden layers are implemented to predict the effect of chemical composition and tensile properties on the both impact toughness and hardness of microalloyed API X70 line pipe steels. The chemical compositions in the forms of "carbon equivalent based on the International Institute of Welding equation (CEIIW)", "carbon equivalent based on the Ito-Bessyo equation (CEPcm)", "the sum of niobium, vanadium and titanium concentrations (VTiNb)", "the sum of niobium and vanadium concentrations (NbV)" and "the sum of chromium, molybdenum, nickel and copper concentrations (CrMoNiCu)", as well...
A parametric study on seismic characteristics of cold-formed steel shear walls by finite element modeling
, Article Advanced Steel Construction ; Volume 10, Issue 1 , 2014 , Pages 53-71 ; ISSN: 1816112X ; Rahmani, A ; Parvaneh, A ; Ronagh, H. R ; Sharif University of Technology
Abstract
Shear wall panels, including cold-formed steel frames and its attached sheathing, are common lateral load resisting systems of cold-formed steel structures. In this paper, the finite element method is used to study the lateral performance of shear wall panels. The finite element model is validated against experimental results of other researchers. Using the validated model, a parametric study is described to determine strength, drift and seismic behavior of the shear wall panels. Based on the results, it is concluded that the initial stiffness and ultimate lateral strength are dramatically affected by the thickness of the frame members, type of sheathing material, edge screw spacing, height...
Welding metallurgy of dissimilar AISI 430/DQSK steels resistance spot welds
, Article Welding Journal ; Volume 94, Issue 6 , 2015 , Pages 203s-210s ; 00432296 (ISSN) ; Marashi, S. P. H ; Alizadeh Sh, M ; Sharif University of Technology
American Welding Society
2015
Abstract
This paper addresses the microstructure and mechanical performance of dissimilar resistance spot welds between AISI 430 ferritic stainless steel and drawing quality special killed (DQSK) low-carbon steel. The mechanical properties of the welds are described by peak load, failure energy, and failure mode during the tensile-shear test. Phase transformations in the fusion zone (FZ) and heat-affected zone (HAZ) are analyzed. The main metallurgical features of the weldment are the formation of a dual-phase, ferrite-martensite microstructure in the FZ, grain growth and martensite formation in the HAZ of the ferritic stainless steel side, and martensitic and eutectoid transformations in the HAZ of...
Effect of microstructure on attenuation mechanism of ultrasonic waves in carbon steels
, Article Materials Science and Technology ; Volume 26, Issue 4 , 2010 , Pages 482-486 ; 02670836 (ISSN) ; Vahid Dastjerdi, H ; Mahdavi, R ; Rasouli, D ; Sharif University of Technology
Abstract
In this paper, fundamental concepts of ultrasonics and characteristics of distinctive microstructures have been used to simply explain the effect of microstructure on the attenuation mechanism of ultrasonic waves in carbon steels. In addition, it has been shown that application of the second medium hardness instead of the bulk hardness is more appropriate to correlate the sound velocity and the microstructure
Study of the effect of fluid flow on corrosion rate for simple carbon steel in aqueous solution using rotating disk electrode
, Article 18th International Congress of Chemical and Process Engineering, CHISA 2008, Prague, 24 August 2008 through 28 August 2008 ; 2008 ; Mohagheghi, A ; Sharif University of Technology
2008
Abstract
The influence of fluid flow on the corrosion of simple carbon steel ST37 (AISI 1020) in aqueous solution of Bandar-Abbas gas well was studied at 25°C under air-saturated condition. The mechanism and kinetic of corrosion in different hydrodynamic conditions were determined using a rotating disk electrode. Increasing the velocity of rotating disk ≤ 1000 rpm caused an augmentation in corrosion rate from 9.89 to 18.95 mill in./yr. Increasing the velocity beyond 1000 rpm changed the corrosion mechanism so that the activation polarization will control the corrosion process, and the variation in corrosion rates was due to various corrosion mechanisms rather than mass transfer of reactant component....
As-cast mechanical properties of vanadium/niobium microalloyed steels
, Article Materials Science and Engineering A ; Volume 486, Issue 1-2 , 2008 , Pages 1-7 ; 09215093 (ISSN) ; Rassizadehghani, J ; Asgari, S ; Sharif University of Technology
2008
Abstract
Tensile and room temperature Charpy V-notch impact tests along with microstructural studies were used to evaluate the variations in the as-cast mechanical properties of low-carbon steels with and without vanadium and niobium. Tensile test results indicate that good combinations of strength and ductility can be achieved by microalloying additions. While the yield strength and UTS increase up to respectively 370-380 and 540-580 MPa in the microalloyed heats, their total elongation range from 20 to 25%. TEM studies revealed that random and interphase fine-scale microalloy precipitates play a major role in the strengthening of the microalloyed heats. On the other hand, microalloying additions...