Search for: austenite-transformations
Article Journal of Materials Processing Technology ; Volume 146, Issue 3 , 2004 , Pages 311-317 ; 09240136 (ISSN) ; Sharif University of Technology
A mathematical model based on the finite element method and additivity rule has been developed to predict temperature history and microstructural changes during cooling of steel. The utilized model considers the effects of various factors including initial austenite grain size and its role on the kinetics of pearlite and ferrite transformations, amount of residual strain within the cooling material, heat of transformation and variation of thermo-physical properties of the steel during cooling. The model can be employed as a guideline to design new cooling programs for achieving the desired microstructure and mechanical properties. To verify the results of the modelling, time-temperature...
Article Materials and Design ; Volume 25, Issue 8 , 2004 , Pages 673-679 ; 02613069 (ISSN) ; Karimi Taheri, A ; Sharif University of Technology
Elsevier Ltd 2004
In this work, a model based on the finite element method and assumption of second order phase transformation has been developed to predict temperature history and austenite decomposition kinetics during continuous cooling of a low carbon steel. In order to accurately assess the temperature field and transformation rate the effects of various factors such as work hardening role on the kinetics of transformation, interconnection between austenite phase change and thermo-physical properties of the steel, and initial austenite grain size have been considered in the model. To verify the results of the modelling, time-temperature histories during cooling of a low carbon steel has been determined...
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
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...
Article Materials Science and Engineering A ; Volume 421, Issue 1-2 , 2006 , Pages 260-267 ; 09215093 (ISSN) ; Sharif University of Technology
In this paper, a mathematical model has been developed to determine temperature distribution on the run-out table. The variational formulation and the finite element method have been employed to solve the governing conduction-convection equation. In order to avoid numerical instabilities due to the convection term, the heat transfer equation is first transformed to the standard form and then Raylieght-Ritz approximation technique and the finite element method have been utilized to solve the equation. To include the effect of phase transformation during cooling of steel, a second-order rate equation for describing austenite decomposition kinetics is coupled with the heat transfer model. A...
Deformation Behavior and Effect of Strain Path on Strain-Induced Martensite Transformation in Austenitic Stainless Steel, M.Sc. Thesis Sharif University of Technology ; Serajzadeh, Siamak
In some of the austenitic stainless steels, the strain-induced martensite transformation occurs during the deformation processing owing to instability of austenite phase at low temperatures. In this study, formation of strain-induced martensite as well as the impact of strain path on the rate of martensite transformation in 316L austenitic stainless steel were investigated. At first, the multi-pass cold rolling experiments at room temperature and -8 ℃ were conducted in which both direct and reverse rolling layouts were taken into account. Then, as the third path, the uni-axial tensile loading with an appropriate strain rate was considered. After that, in order to examine the mechanical and...
Damage development during the strain induced phase transformation of austenitic stainless steels at low temperatures, Article Modelling and Simulation in Materials Science and Engineering ; Volume 29, Issue 4 , 2021 ; 09650393 (ISSN) ; Ganjiani, M ; Sasani, F ; Sharif University of Technology
IOP Publishing Ltd 2021
The strain-induced martensitic transformation greatly affects the plastic behavior of the metastable austenitic stainless steels. The martensitic transformation continuously changes the initially homogeneous material into a strongly heterogeneous bi-phase one. In addition to the hardening behavior, this phenomenon would influence the damage growth and load-carrying capacity of the material during the plastic deformation. In this study, plastic behavior of the material AISI 304 including the hardening and damage growth, has been examined at low temperature; where a high rate of martensitic transformation affects the microstructure strongly. Experimental analysis and microscopic observations...
Welding metallurgy of stainless steels during resistance spot welding part II –heat affected zone and mechanical performance, Article Science and Technology of Welding and Joining ; Volume 20, Issue 6 , 2015 , Pages 512-521 ; 13621718 (ISSN) ; Pouranvari, M ; Marashi, S. P. H ; Sharif University of Technology
Maney Publishing 2015
Implementation of new materials in automotive body-in-white requires through knowledge of their metallurgical response to welding process thermal cycle. This two-part paper aims at understanding the physical and mechanical metallurgy of stainless steels, as interesting candidates for automotive application, during resistance spot welding. The second part addresses the phase transformations in the heat affected zone of three types of stainless steels including austenitic, ferritic and duplex steels. Failure modes and mechanical properties of stainless steel resistance spot welds are discussed. The peak load and energy absorption of stainless steel resistance spot welds are compared with...
Article Science and Technology of Welding and Joining ; Volume 20, Issue 6 , Mar , 2015 , Pages 502-511 ; 13621718 (ISSN) ; Alizadeh Sh, M ; Marashi, S. P. H ; Sharif University of Technology
Maney Publishing 2015
Weldability is one of the key requirements for automotive materials. This two-part paper aims at understanding the metallurgical phenomena during resistance spot welding of stainless steels, as interesting candidates for automotive body in white. Part I addresses the phase transformations in the fusion zone of three types of stainless steels including austenitic, ferritic and duplex types. The solidification and solid state phenomena including columnar to equiaxed transition, ferrite– austenite post-solidification transformation, martensitic transformation and carbide precipitation are discussed. Particular attention is given to the effect of high cooling rate of resistance spot welding...
Microstructural evolution during ultra-rapid annealing of severely deformed low-carbon steel: strain, temperature, and heating rate effects, Article International Journal of Minerals, Metallurgy and Materials ; Volume 23, Issue 7 , 2016 , Pages 779-792 ; 16744799 (ISSN) ; Kazeminezhad, M ; Sharif University of Technology
University of Science and Technology Beijing
An interaction between ferrite recrystallization and austenite transformation in low-carbon steel occurs when recrystallization is delayed until the intercritical temperature range by employing high heating rate. The kinetics of recrystallization and transformation is affected by high heating rate and such an interaction. In this study, different levels of strain are applied to low-carbon steel using a severe plastic deformation method. Then, ultra-rapid annealing is performed at different heating rates of 200–1100°C/s and peak temperatures of near critical temperature. Five regimes are proposed to investigate the effects of heating rate, strain, and temperature on the interaction between...
Ferritic-austenitic stainless steels dissimilar resistance spot welds: Metallurgical and failure characteristics, Article Science and Technology of Welding and Joining ; Volume 21, Issue 6 , 2016 , Pages 438-445 ; 13621718 (ISSN) ; Khorramifar, M ; Hoveida Marashi, S. P ; Sharif University of Technology
Taylor and Francis Ltd 2016
The paper addresses the microstructure and failure characteristics of dissimilar resistance spot welds between austenitic stainless steel and ferritic stainless steel. The fusion zone (FZ) of dissimilar welds exhibited complex microstructure consisting of ferrite, austenite and martensite. The development of this triplex structure in the FZ was explained by analysing the phase transformation path and austenite stability. Results showed that all dissimilar welds failed in partial thickness-partial pull-out failure mode. It was shown that the fraction of the nugget fracture of the weld is reduced by increasing the FZ size improving the mechanical performance of the weld. Peak load and energy...
Article Welding Journal ; Volume 96, Issue 9 , 2017 , Pages 307s-318s ; 00432296 (ISSN) ; Pouranvari, M ; Movahedi, M ; Sharif University of Technology
This paper investigates the metallurgical and mechanical response of 2304 duplex stainless steel-as an interesting candidate for automotive body-in-white applications-to resistance spot welding. The results showed the high cooling rate associated with the resistance spot welding process suppressed the postsolidification ferrite-austenite transformation leading to improper ferrite-austenite phase balance with a reduced volume fraction of austenite and consequent precipitation of chromium-rich nitrides. The effects of welding current, as the key parameter determining the weld heat input, on the austenite volume fraction and precipitation are discussed. The minimum fusion zone hardness...
Effects of severe plastic deformation on pre-osteoblast cell behavior and proliferation on AISI 304 and Ti-6Al-4V metallic substrates, Article Surface and Coatings Technology ; Volume 366 , 2019 , Pages 204-213 ; 02578972 (ISSN) ; Aydın, H. M ; Maleki, E ; Varol, R ; Unal, O ; Sharif University of Technology
Elsevier B.V 2019
In this study, titanium alloy (Ti-6Al-4V) and austenitic stainless steel (AISI 304) biomedical alloys were subjected to surface severe plastic deformation (SSPD) via severe shot peening (SSP) with the conditions of A28-30 Almen intensity. SSP is widely accepted as much more effective than the conventional surface modification techniques since it forms a nano-grain layer with large number of dislocations and grain boundaries. The SSP treatment in this study was led to a very thin rough layer in Ti-6Al-4V titanium alloy compared to that of AISI 304. The thicker layer of AISI 304 was created by twin-twin intersections and a martensite structure transformations. SSP treatment was resulted in a...
Pathways to improve the austenite–ferrite phase balance during resistance spot welding of duplex stainless steels, Article Science and Technology of Welding and Joining ; Volume 24, Issue 1 , 2019 , Pages 8-15 ; 13621718 (ISSN) ; Pouranvari, M ; Movahedi, M ; Sharif University of Technology
Taylor and Francis Ltd 2019
Microstructure evolution mechanism and corrosion behavior of transient liquid phase bonded 304l stainless steel, Article Metals and Materials International ; Volume 27, Issue 9 , 2021 , Pages 3417-3431 ; 15989623 (ISSN) ; Binesh, B ; Sharif University of Technology
Korean Institute of Metals and Materials 2021
Abstract: Transient liquid phase (TLP) bonding of 304L austenitic stainless steel was carried out using MBF-20 interlayer at 1070 °C with different holding times. The effect of bonding time on the microstructure and corrosion resistance of the TLP bonded samples was investigated aiming to obtain the optimal bonding time. The results showed that isothermal solidification was completed within 45 min at 1070 °C and shorter holding times gave rise to the formation of intermetallic compounds at the joint centerline. It was found that the solidification sequence in the joint region is as follows: (1) isothermal solidification of γ solid solution, (2) formation of ternary eutectic of γ + Ni boride...