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dual-phase-steel
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A study on the microstructural changes in hot rolling of dual-phase steels
, Article Journal of Materials Science ; Volume 41, Issue 7 , 2006 , Pages 1917-1925 ; 00222461 (ISSN) ; Serajzadeh, S ; Taheri, A. K ; Sharif University of Technology
2006
Abstract
In this study, hot rolling behavior of a low alloy steel in the dual-phase region is studied. The effects of various process parameters such as initial temperature, soaking time, rolling speed and the cooling conditions are investigated. Then, mechanical testing and microstructural studies are performed and the effects of process parameters are studied and finally the optimum rolling program is determined based on the achieved results. The results show that rolling speed significantly alters the final microstructures and mechanical properties. Higher rolling speed results higher volume fraction of ferrite phase. In addition, the optimum dual-phase microstructure for this steel can be...
Intercritical heat treatment temperature dependence of mechanical properties and corrosion resistance of dual phase steel
, Article Materials Research ; Volume 22, Issue 1 , 2019 ; 15161439 (ISSN) ; Behroozi, M ; Marashi, P ; Ranjbarnodeh, E ; Pouranvari, M ; Sharif University of Technology
Universidade Federal de Sao Carlos
2019
Abstract
This study investigated the effect of intercritical heat treatment temperature on the tensile properties, work hardening and corrosion resistance of dual phase steel. Ferrite-martensite dual phase steel with different martensite volume fractions were obtained after heat treatment at different intercritical temperatures. Microstructure, mechanical properties of steel were measured and the corrosion resistance was evaluated via polarization test. Tensile strength of the specimens increased by increasing the martensite volume fraction up to 48.2%. Further increase in martensite volume fraction led to decrease in tensile strength. Work hardening behavior analyzing showed that in DP steel with...
The effect of cold-rolling prior to the inter-critical heat treatment on microstructure and mechanical properties of 4340 steel with ferrite – Martensite microstructure
, Article Materials Science and Engineering A ; Volume 830 , 2022 ; 09215093 (ISSN) ; Ekrami, A ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
This study investigates the effect of cold rolling prior to inter-critical annealing on microstructure and mechanical properties of ferrite-martensite dual phase steel. Samples were heated to 850 °C for 1 h followed by oil quenching, then the steel sheet were cold rolled by 0%,10%,15% and 20% reduction in thickness. The inter-critical annealing treatment (750 °C, 120min) was performed to generate a ferrite-martensite microstructure. Microstructural studies showed that increasing the applied cold rolling, leading to increase in volume fraction of martensite and decrease in ferrite grain size. Mechanical properties of dual phase steel were measured by tensile, impact and hardness tests....
The Effect of Pressure on Microstructure and Mechanical Properties of TLP Bonded Dual Phase Steels
, M.Sc. Thesis Sharif University of Technology ; Ekrami, Ali Akbar (Supervisor)
Abstract
Dual Phase ferritic-martensitic steels are kind of high strength low alloy steels (HASLA) which are widely used in industry because of their strength and formability. Since welding of dual phase steels in conventional welding methods causes structural change and Subsequently alters mechanical properties of both weld zone and heat affected zone(HAZ), additional operations which are not commercially viable is needed to achieve a dual phase structure in structurally changed regions. In this study, transient liquid phase (TLP) bonding method is used during dual phasing process in order to preserve dual phase ferritic-martensitic structure and avoid extra heat treatment. Applied pressure during...
The Effect of Interlayer Composition on Microstructure and Mechanical Properties of Transient Liquid Phase Bonded Dual Phase Steels
, M.Sc. Thesis Sharif University of Technology ; Ekrami, Ali Akbar (Supervisor)
Abstract
Interlayer composition as one of the most important factors of TLP bonding could affect bonding region composition and microstructure that both of them govern the mechanical properties of the joint. Due to the risk of substrate microstructure degradation , welding of dual phase steel needs more cautions. TLP bonding ideally acquires joints having more similar microstructure to substrate. Moreover , using this method could avoid the change of base metal microstructure when heat treatment of carbon steel is postponed until after bonding. Fe-based , Ni-based and commercially pure Cu are three different composition has been studied in this work. The bonded samples were investigated by optic and...
The Effect of Interlayer Thickness on Microstructure and Mechanical Properties of TLP Bonding on Dual Phase Steel
, M.Sc. Thesis Sharif University of Technology ; Ekrami, Ali Akbar (Supervisor)
Abstract
In this study, the effect of the Cu interlayer thickness was studied on St52 steel. Specimens with different thickness of the interlayer, were subjected to 1150 °C at different times. Isothermal solidification was completed for the thickness of the 50 μm, 30 μm, and 10 μm in 30, 25 and 20 minutes. Afterwards, homogenizing and dual-phase heat treatment were used for 75 minutes at 730°C. Optical microscopy and SEM were used to analyze the microstructure of the joints. Mechanical properties of the joints, including micro hardness of different parts of the joint and also shear strength of the joint zone were studied. The results show that after homogenizing treatment, microstructure and harness...
High temperature mechanical properties of dual phase steels
, Article Materials Letters ; Volume 59, Issue 16 , 2005 , Pages 2070-2074 ; 0167577X (ISSN) ; Sharif University of Technology
2005
Abstract
Dual phase steels with different martensite volume fraction and morphology were tensile tested at temperature range of 25-550 °C. Stress-strain curves of all steels showed serration flow at temperature range of 250-450 °C and smooth flow at the other temperatures. Both yield and ultimate tensile strengths increased with increasing testing temperature up to about 450 °C and then decreased at higher temperatures. At a given temperature, yield stress, tensile strength, and work hardening increased with increasing volume fraction of martensite. Similar behavior was observed by changing martensite morphology from network to fibrous martensite. The change in mechanical properties was related to...
Room-temperature mechanical properties of dual-phase steels deformed at high temperatures
, Article Materials Letters ; Volume 59, Issue 14-15 , 2005 , Pages 1828-1830 ; 0167577X (ISSN) ; Vahdani, H ; Sharif University of Technology
2005
Abstract
Dual-phase steels with different morphology and volume fraction of martensite were deformed between 2% and 8% at a high-temperature range of 150-450 °C. Room-temperature tensile properties showed that both yield and tensile stresses depend on the amount of pre-strain, deformation temperature, volume fraction and morphology of martensite. Results show that both YS and UTS increase with increasing the amount of pre-strain at a given temperature. © 2005 Elsevier B.V. All rights reserved
The effect of dynamic strain aging on room temperature mechanical properties of high martensite dual phase (HMDP) steel
, Article Materials Science and Engineering A ; Volume 550 , 2012 , Pages 325-332 ; 09215093 (ISSN) ; Koohbor, B ; Ahadi, K ; Ekrami, A ; Khakian Qomi, M ; Izadyar, T ; Sharif University of Technology
Elsevier
2012
Abstract
AISI 4340 steel bars were heated at 900 °C for one hour, annealed at 738 °C for different durations and oil-quenched in order to obtain dual phase steels with different ferrite volume fractions. A 3% prestrain at the temperature range of 150-450 °C was then imposed to the samples, and room temperature tensile tests were carried out, afterwards. Results indicate that the maximum values for both yield and ultimate tensile strength would exist for the samples pre-strained at the temperature range of 250-300 °C. Also, a sudden drop of the ductility was observed at the mentioned temperature range. The observed behavior might be attributed to the occurrence of dynamic strain aging taken place at...
Effect of martensite volume fraction on work hardening behavior of triple phase (TP) steels
, Article Materials Science and Engineering A ; Volume 528, Issue 13-14 , 2011 , Pages 4422-4426 ; 09215093 (ISSN) ; Ekrami, A ; Sharif University of Technology
2011
Abstract
The strain hardening behavior of AISI 4340 steel with dual phase (DP) and triple phase (TP) microstructures with constant ferrite volume fractions of 34% was investigated. The microstructures of specimens were analyzed using an optical microscope. The tensile flow behavior of all the samples was explained using Holloman equation. Results showed that in both DP and TP steels, work hardening takes place in two stages. The onset strain of second stage of work hardening and Holloman equation parameters (work hardening exponent and strength coefficient) in both stages were increased with the increase of martensite volume fraction in TP steels. At first stage of work hardening, ferrite phase...
Peak load and energy absorption of DP600 advanced steel resistance spot welds
, Article Ironmaking and Steelmaking ; 2016 , Pages 1-8 ; 03019233 (ISSN) ; Pouranvari, M ; Salim, R. K ; Hashim, F. A ; Hoveida Marashi, S. P ; Sharif University of Technology
Taylor and Francis Ltd
2016
Abstract
The paper aims at investigating the microstructure, failure mode transition, peak load and energy absorption of DP600 dual phase steel during the tensile-shear test. It was found that the welding current has profound effect on the load–displacement characteristics. In the low welding current, welds failed in interfacial failure mode. Increasing welding current resulted in sufficient weld nugget growth to promote double-sided pullout failure mode with improved mechanical properties. Further increase in the welding current caused expulsion and failure mode was changed to single-sided pullout with reduced energy absorption capability. It was found that the fusion zone size is the key parameter...
Comparison of mechanical properties of martensite/ferrite and bainite/ferrite dual phase 4340 steels
, Article Materials Science and Engineering A ; Volume 523, Issue 1-2 , 2009 , Pages 125-129 ; 09215093 (ISSN) ; Ekrami, A ; Sharif University of Technology
2009
Abstract
Different microstructures were produced by heat treatment of 4340 steel. These microstructures are bainite, martensite, ferrite-martensite and ferrite-bainite. Mechanical tests were carried out at room temperature. The results showed that steel with bainite-ferrite microstructure has better ductility and charpy impact energy than steels with martensite-ferrite and full bainite microstructures. But yield and tensile strengths of this steel are less than the yield and tensile strengths of the other two steels. Hardness measurements showed that their hardness is the same. Fracture surface observations of tensile specimens showed increase in toughness of bainite-ferrite in comparison to...
Microstructure and mechanical properties of pure Cu interlayer TLP joints of 304 stainless steel to dual phase steel
, Article Journal of Materials Processing Technology ; Volume 275 , January , 2020 ; Ekrami, A ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Bonding was carried out at 1150 °C for holding times of 60 and 90 min followed by water quenching. At the bonding time of 60 min, Cu remained at the bond region resulting in an unstable liquid/solid interface with a sinusoidal microstructure. Isothermal solidification completed at the holding time of 90 min. Unidirectional solidification was observed from the stainless steel side toward the low carbon manganese steel and abnormal grain growth of stainless steel was seen at the bond region due to temperature gradient which originated from different electrical properties of the parent alloys. Joints made at the bonding time of 90 min were homogenized at 730 °C for 75 min and quenched in water...
Friction stir welding of advanced high strength dual phase steel: Microstructure, mechanical properties and fracture behavior
, Article Materials Science and Engineering A ; Volume 769 , January , 2020 ; Kokabi, A. H ; Goodarzi, M ; Kestens, L. A. I ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
In this study, butt welds of an advanced high strength dual phase steel were fabricated using friction stir welding at a constant rotational speed of 800 rpm and different transverse speeds of 100, 150 and 200 mm/min. It was observed that sound welds can be obtained at transverse speeds of 100 and 150 mm/min. At transverse speed of 100 mm/min, the entire stir zone processed at temperatures higher than Ac3. By increasing transverse speed to 150 mm/min, temperature in the bottom region of the stir zone lied between Ac1 and Ac3, while the middle and the top regions experienced temperatures higher than Ac3. The lower peak temperature in the bottom region of the stir zone resulted in finer and...
The effect of bainite volume fraction on wear behavior of aisi 4340 ferrite–bainite dual-phase steel
, Article Journal of Materials Engineering and Performance ; Volume 31, Issue 11 , 2022 , Pages 8687-8698 ; 10599495 (ISSN) ; Ekrami, A ; Sharif University of Technology
Springer
2022
Abstract
The tribological behaviors of an AISI 4340 ferritic-bainitic dual-phase steel with different bainite (VB) content were investigated. The effects of VB on wear resistance and the corresponding wear mechanisms were investigated using a pin-on-disk wear testing machine, at normal loads of 10 and 50 N, at a constant sliding velocity. The tensile and hardness tests showed that the yield strength, ultimate tensile strength, and hardness increased with increasing the VB. The wear test results at the 10 N normal load showed a direct correlation between the tensile and tribological behavior of the samples. Nevertheless, at the normal load of 50 N, unexpected behavior was observed due to the carbon...
The Effect of Martensite Morphology on Mechanical Properties of TLP Bonded Dual Phase Steels
, M.Sc. Thesis Sharif University of Technology ; Ekrami, Ali Akbar (Supervisor) ; Kokabi, Amir Hossein (Supervisor)
Abstract
In the present study the production of ferrite-martensite dual-phase (DP) Steel was investigated during the bonding process by transient liquid phase method. The effect of martensite morphologies on mechanical properties of bonding zone were also studied. To make the bonding process and DP steel production heat treatment cycle simultaneously, the step in which the isothermal solidification completed, bonding process, was done simultaneously with austenitising of the steel. Homogenizing of the bond zone, was also done with DP steel making at the intercritical temperature. The St52 steel was utilized for producing DP steel and for bonding process, iron base interlayer with melting point of...
The Effect of Ferrite Grain Size on Tlp Bonding Time of Dual Phase Steels
, M.Sc. Thesis Sharif University of Technology ; Ekrami, Ali Akbar (Supervisor)
Abstract
In this study, low carbon steels were joined with TLP bonding method; using a Fe based interlayer. Transient Liquid Phase bonding is a diffusional process in which as tempreture rises a melting point depressant element difuses in to the base metal and as a result the interlayer will isothermally solidify. Due to the fact that Ferrite grain size can effect the amount of diffusion which is taking place, in this study the effect of this variable on the isothermal solidification time was investigated using steels with different initial grain sizes. Microstructural studies indicated that as the mean grain size increases the time needed for the isothermal solidification to complete increases....
Transient Liquid phase Bonding of Low Carbon Mangenese Steel to Austenitic Stainless Steel by Pure Cu Foil
, M.Sc. Thesis Sharif University of Technology ; Ekrami, Ali Akbar (Supervisor) ; Seyyed Reihani, Morteza (Supervisor)
Abstract
In the present research, transient liquid phase bonding of dissimilar st52 low carbon manganese steel to 304 stainless steel by pure Cu foil, in induction furnace and SIC furnace, was investigated. Samples were bonded in induction and SIC furnace at 1150 0C for different bonding times. Samples were then cut transversely and cross section of samples was examined by optical and scanning electron microscope. Complete isothermal solidification time was more than 9 hours and 90 minutes for SIC and induction furnace, respectively. Micro hardness and shear strength tests were done on samples bonded in optimum condition. Shear strength of none homogenized samples which had been bonded in SIC...
TLP Bonding of Ferrite - Martensite Dual Phase Steel and Comparison with Fusion Welding Method
, M.Sc. Thesis Sharif University of Technology ; Ekrami, Ali Akbar (Supervisor)
Abstract
In this study, low carbon plain steels joined with TLP bonding method using Fe-44Ni-7B-4Mo interlayer, The bonding parameters (holding time, temperature) have been changed to find optimum conditions of TLP bonding. Microstructure and properties of joints have also been investigated. Dual phase processing of the used steel has been carried out during joints homogenization. Microstructural studies with scanning electron microscope and optical microscope showed that isothermal solidification completed at holding for 50 minutes at the bonding temperature of 1180℃. These parameters are taken as optimum conditions of TLP bonding. Microstructure of the isothermally solidified zone (joint region)...
Investigation on Effects of Cold Roll Prior to Intercritical Annealing on Microstructure and Mechanical Properties of Ferrite-Martensite Dual Phase Steel
, M.Sc. Thesis Sharif University of Technology ; Ekrami, Ali Akbar (Supervisor)
Abstract
This study investigates effect of cold roll prior to inter-critical annealing on microstructure and mechanical properties of ferrite-martensite dual phase steel. Samples were heated to 850oC for 1h followed by oil quench, then the steel sheet were cold rolled by 0%,10%,15% and 20% reduction in thickness, Then an inter-critical annealing(750oC,120min) was performed to generate a ferrite-martensite microstructure. Microstructural study showed that increase in applied Cold roll, leading to increase volume fraction of martensite and decrease in ferrite grain size. Mechanical properties of dual phase steel were tested by Tensile test, impact test and micro-hardness Test. Results shows that...