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martensitic-steels
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Total 21 records
Creating a Protective Coating Against Corrosion and Erosion on the Surface of the Parts using in Sour Environments
, M.Sc. Thesis Sharif University of Technology ; Kokabi, Amir Hossein (Supervisor)
Abstract
A concern in the production sour oil and gas is the corrosion caused by the acid gas H2S. Even though corrosion resistant alloys (CRA) have long been available as a material selection option that mitigates H2S corrosion, the carbon steel is in general more cost-effective for oil and gas facilities. The aim of this study is to investigate the mechanical properties of 410NiMo cladding on a low alloy steel substrate. In this investigation, two successive layers of ER410NiMo were clad on low alloy steel substrates. To reduce the likelihood of Hydrogen Induced Cracking (HIC) and producing stable hydrogen traps, Post Weld Heat Treatment (PWHT) was used. To characterize the mechanical properties of...
Upset Resistance Welding of Duplex Stainless Steel to Martensitic Stainless Steel
, M.Sc. Thesis Sharif University of Technology ; Movahedi, Mojtaba (Supervisor)
Abstract
Upset Resistance Welding (URW) is a solid-state joining process which can be used to join a variety of parts and profiles including railways, wheel rims and pipes used in oil and petrochemical industries. This process has three primary parameters, welding current, current passage time and mechanical pressure. Martensitic Stainless Steels (MSSs) due to high strength and wear resistance, good atmospheric corrosion resistance and relatively low price and Duplex Stainless Steels (DSSs) because of higher strength and better corrosion resistance in chlorine environments, are widely used in different industries. Dissimilar MSS/DSS joints are of great importance for piping, specially in oil and...
Welding metallurgy of martensitic advanced high strength steels during resistance spot welding
, Article Science and Technology of Welding and Joining ; Volume 22, Issue 4 , 2017 , Pages 327-335 ; 13621718 (ISSN) ; Pouranvari, M ; Movahedi, M ; Sharif University of Technology
Abstract
The paper addresses the process–microstructure–performance relationships in resistance spot welding of a martensitic advanced high strength steel. Significant softening was observed in the heat affected zone (HAZ) due to allotriomorphic ferrite formation in the inter-critical HAZ and tempering of martensite in sub-critical HAZ (SCHAZ), with the latter plays more important role in mechanical properties of the spot welds. The strain concentration associated with the HAZ softening promotes initiation of pullout failure from the soft SCHAZ. While, the peak load in the interfacial failure mode is governed by the fusion zone size, that of the pullout mode is significantly affected by the HAZ...
Resistance spot welding of MS1200 martensitic advanced high strength steel: microstructure-properties relationship
, Article Journal of Manufacturing Processes ; Volume 31 , 2018 , Pages 867-874 ; 15266125 (ISSN) ; Sobhani, S ; Goodarzi, F ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
This paper addresses the microstructure and tensile-shear mechanical performance of MS1200 Giga-grade martensitic advanced high strength steel resistance spot welds. The key phase transformations in MS1200 welds were lath martensite formation in the fusion zone (FZ) and upper-critical heat affected zone (HAZ), new ferrite formation in the inter-critical HAZ and martensite tempering in the sub-critical HAZ. The MS1200 welds were featured by a near matching hardness in the fusion zone and under-matching hardness in the heat affected zone (HAZ) compared to the base metal. At certain process window a complete nugget pullout and separation was observed with high post-necking tearing energy. The...
Microstructure and Mechanical Properties of AA6061-T6/Ti6Al4V Joints by Resistance Spot Welding
, M.Sc. Thesis Sharif University of Technology ; Kokabi, Amir Hossein (Supervisor) ; Pouranvari, Majid (Supervisor)
Abstract
Titanium alloy and aluminum alloy 6061-T6 were successfully joined by resistance spot welding. The microstructure and mechanical properties of the lap joint were investigated. The microstructure of joints was inspected by OM, XRD, and SEM. The results reveal that the reaction between liquid aluminum and solid titanium were caused welding-brazing joints, which restricts the formation of IMCs. The microstructure in the aluminum side is a type of transition structure, which is considered to be the same microstructure that connects the columnar dendrite and Equiaxed dendrite in similar aluminum alloy RSW. The welding current has the most significant influence upon the tensile shear and cross...
, M.Sc. Thesis Sharif University of Technology ; Movahedi, Mojtaba (Supervisor)
Abstract
Martensitic stainless steels with high strength, good corrosion resistance and formability in the annealed condition are good choices for automotive applications, but they suffer from low weldability due to high hardenability and formation of brittle martensite without tempered structure in the weld metal and heat affected zone (HAZ). In other word, martensitic stainless steels have the worst weldability among all kinds of stainless steels. On the other hand, resistance spot welding is the main method for joining sheets in the automotive industry. Therefore, in the present work, microstructure and mechanical properties of the resistance spot welds of AISI 420 martensitic stainless steel in...
Anisotropy of retained austenite stability during transformation to martensite in a TRIP-assisted steel
, Article Steel Research International ; Volume 84, Issue 3 , 2013 , Pages 297-303 ; 16113683 (ISSN) ; Akbarzadeh, A ; Petrov, R ; Zhao, L ; Sharif University of Technology
2013
Abstract
Retained austenite as a key constituent in final microstructure plays an important role in TRansformation Induced Plasticity (TRIP) steels. The volume fraction, carbon concentration, size, and morphology of this phase are the well-known parameters which effects on the rate of transformation of retained austenite to martensite and the properties of steel, are studied by many researchers. Of the transformation of retained austenite to martensite under strain in a TRIP steel is studied in this paper. The experimental results show that the transformation rate of retained, austenite with similar characteristics, to martensite in differently processed TRIP steel samples, exhibits an anisotropic...
Influence of martensite volume fraction on impact properties of triple phase (TP) steels
, Article Journal of Materials Engineering and Performance ; Volume 22, Issue 3 , 2013 , Pages 823-829 ; 10599495 (ISSN) ; Ekrami, A ; Sharif University of Technology
2013
Abstract
Ferrite-bainite-martensite triple phase (TP) microstructures with different volume fractions of martensite were obtained by changing heat treatment time during austempering at 300 C. Room temperature impact properties of TP steels with different martensite volume fractions (VM) were determined by means of Charpy impact testing. The effects of test temperature on impact properties were also investigated for two selected microstructures containing 0 (the DP steel) and 8.5 vol.% martensite. Test results showed reduction in toughness with increasing VM in TP steels. Fracture toughness values for the DP and TP steels with 8.5 vol.% martensite were obtained from correlation between fracture...
Thermal stability investigation of expanded martensite
, Article Surface and Coatings Technology ; Volume 300 , 2016 , Pages 87-94 ; 02578972 (ISSN) ; Bahmannezhad, B ; Nikpoor, N ; Asgari, S ; Sharif University of Technology
Elsevier
2016
Abstract
The aim of this work is to investigate thermal stability of expanded martensite. For this purpose, two martensitic stainless steels, PH 17-4 and 13-8Mo, were low temperature gas carburized. After heat treatment, it was found out that thermal stability of expanded layer of PH 17-4 is higher than that of PH 13-8Mo. Auger Electron Spectroscopy and microhardness machines were used to investigate carbon concentration and hardness of samples, respectively. X-ray diffraction was done to study crystal structures of samples before and after heat treatment
Improving the Failure Behavior of High Strength and High Hardenable Steels Resistance Spot Welds
, M.Sc. Thesis Sharif University of Technology ; Pouranvari, Majid (Supervisor)
Abstract
Selecting materials is a key stage for designing vehicles. Today, advanced high-strength steels and stainless steels are attractive by the automotive industry. In this study, the improvement of mechanical properties of the martensitic stainless steels (MSS420 with annealed condition) and advanced high strength martensitic steels (MS1400 with quenched condition), which have a different response to mechanical tests, were investigated. The welding of MSS420 steel was carried out in three phases. In the first phase, the MSS420 double pulse welding with variable second pulse times (0.2s-1.8s) with a constant secondary pulse current of 4 kA and in the second phase a double pulse welding with...
Study on microstructure and mechanical characteristics of low-carbon steel and ferritic stainless steel joints
, Article Materials Science and Engineering A ; Vol. 608, issue , 2014 , pp. 35-45 ; ISSN: 09215093 ; Mostafaei, M. A ; Pouraliakbar, H ; Kokabi, A. H ; Sharif University of Technology
Abstract
In this work, examinations on the microstructure and mechanical properties of plain carbon steel and AISI 430 ferritic stainless steel dissimilar welds are carried out. Welding is conducted in both autogenous and using ER309L austenitic filler rod conditions through gas tungsten arc welding process. The results indicate that fully-ferritic and duplex ferritic-martensitic microstructures are formed for autogenous and filler-added welds, respectively. Carbide precipitation and formation of martensite at ferrite grain boundaries (intergranular martensite) as well as grain growth occur in the heat affected zone (HAZ) of AISI 430 steel. It is found that weld heat input can strongly affect grain...
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...
Microstructure-toughness relationship in AISI4340 steel
, Article Defect and Diffusion Forum ; Volume 312-315 , 2011 , Pages 110-115 ; 10120386 (ISSN) ; 9783037851173 (ISBN) ; Ekrami, A ; Sharif University of Technology
Abstract
To improve the strength and toughness of AISI 4340 steel, different microstructures, containing full bainite, bainite-ferrite, martensite-ferrite and full martensite were produced by different heat treatment cycles. Tensile, impact and hardness tests were carried out at room temperature. The ductile-brittle transition temperature was determined from impact data at different temperatures. The results showed that steel with bainite - 0.34 ferrite microstructure has the highest elongation and charpy impact energy, while its tensile strength and yield stress decreased in comparison to other microstructures. This increment was noticeable when bainite - 0.34 ferrite steel was tempered. The...
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...
The effect of dynamic strain aging on subsequent mechanical properties of dual-phase steels
, Article Journal of Materials Engineering and Performance ; Volume 19, Issue 4 , June , 2010 , Pages 607-610 ; 10599495 (ISSN) ; Ekrami, A ; Sharif University of Technology
2010
Abstract
Dual-phase (DP) steels with different martensite contents were produced by subjecting a low carbon steel to various heat treatment cycles. In order to investigate the effect of dynamic strain aging (DSA) on mechanical properties, tensile specimens were deformed 3% at 300 °C. Room temperature tensile tests of specimens which deformed at 300 °C showed that both yield and ultimate tensile strengths increased, while total elongation decreased. The fatigue limit increased after pre-strain in the DSA temperature range. The effects of martensite volume fraction on mechanical properties were discussed
Effect of starting microstructure through severe plastic deformation and Ultra-Rapid annealing of Low-Carbon steel
, Article Steel Research International ; Volume 87, Issue 11 , 2016 , Pages 1527-1533 ; 16113683 (ISSN) ; Kazeminezhad, M ; Sharif University of Technology
Wiley-VCH Verlag
Abstract
In this research, low-carbon steel sheets with two different microstructures containing carbides (as-received steel) and pearlites (austenitized steel) are subjected to severe plastic deformation (SPD), and ultra-rapid annealing (URA) is applied with the heating rate of 200 °C s−1 up to the intercritical temperature near Ac1. Microstructure of SPDed as-received steel after URA is consisted of fully refined ferrite grains surrounded by fine pearlites; but for SPDed austenitized steel, grain refinement is not observed, and microstructure is consisted of martensite and high fraction of coarse non-recrystallized ferrite. Presence of carbides for SPDed as-received steel leads to strong...
In situ postweld heat treatment of transformation induced plasticity steel resistance spot welds
, Article Science and Technology of Welding and Joining ; Volume 23, Issue 1 , 2018 , Pages 71-78 ; 13621718 (ISSN) ; Pouranvari, M ; Abedi, A ; Ghaderi, A. A ; Sharif University of Technology
Taylor and Francis Ltd
2018
Abstract
Transformation-induced plasticity (TRIP) steel resistance spot welds are delicate to low-energy interfacial failure via crack propagation through martensitic fusion zone during cross-tension (CT) loading. This paper addresses the effect of three different types of in situ postweld heat treatment (PWHT) on the mechanical properties of TRIP steel resistance spot welds. Depending on the post weld second pulse current level, three different strengthening mechanisms were found including (i) martensite tempering with reduced hardness, (ii) refining of martensite packets with improved toughness and (iii) nugget re-melting/enlargement combined with possible reduction of grain boundary impurity...
Influence of martensite volume fraction on tensile properties of triple phase ferrite-bainite-martensite steels
, Article Materials Science and Engineering A ; Volume 530, Issue 1 , 2011 , Pages 440-445 ; 09215093 (ISSN) ; Ekrami, A ; Sharif University of Technology
2011
Abstract
This paper presents the effect of martensite volume fraction (VM) on mechanical properties of AISI 4340 steel with ferrite-bainite-martensite microstructures. The steel bars were austenitized at 900°C for 1h followed by intercritical annealing at 740°C for 100min and quenching into a salt bath with temperature of 300°C and holding at different times to obtain triple phase (TP) microstructures with 34vol.% fraction ferrite and various martensite (or bainite) contents. Presence of three phases in adjacent to each other was confirmed by metallographic analysis and TEM studies. TEM observation also indicates higher density of dislocations within ferrite near martensite colonies compared to that...
An investigation to effective parameters on the damage of dual phase steels by acoustic emission using energy ratio
, Article World Academy of Science, Engineering and Technology ; Volume 46 , 2010 , Pages 638-643 ; 2010376X (ISSN) ; Khamedi, R ; Sharif University of Technology
2010
Abstract
Dual phase steels (DPS)s have a microstructure consisting of a hard second phase called Martensite in the soft Ferrite matrix. In recent years, there has been interest in dual-phase steels, because the application of these materials has made significant usage; particularly in the automotive sector Composite microstructure of (DPS)s exhibit interesting characteristic mechanical properties such as continuous yielding, low yield stress to tensile strength ratios(YS/UTS), and relatively high formability; which offer advantages compared with conventional high strength low alloy steels(HSLAS). The research dealt with the characterization of damage in (DPS)s. In this study by review the mechanisms...