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Investigation on Pulsed TIG Lap Welding of Al-5052 Sheet to Al-1050 Clad St-12 Sheet
, M.Sc. Thesis Sharif University of Technology ; Movahhedi, Mojtaba (Supervisor)
Abstract
In this study, Al-5052 aluminium alloy sheet was lap joined to aluminium clad steel sheet using pulsed gas tungsten arc welding and Al-Si filler metal. Effect of heat-input, thickness of clad layer and frequency were investigated on the formation of intermetallic reaction layer, microstructure of the weld seam and shear strength of the joints are explored. Stress analysis in weld is also used in order to justify the fracture location in the welds the microstructure and shear-tensile strength of the welds (joining with A1-1050 clad layer with two thickness of 350 μm and 1000 μm). Before welding, aluminum clad steel sheets were produced by roll bonding and 450 °C annealing temperature and 90...
Experimental and Numerical study on Resistance Spot Welding of Aluminum to Aluminum Clad Steel Sheet
, M.Sc. Thesis Sharif University of Technology ; Movahedi, Mojtaba (Supervisor) ; Serajzadeh, Siamak (Supervisor)
Abstract
Resistance spot welding is one of the types of sheet metal joining processes used in many industries, such as automotive, home appliances, and aviation. In the direct welding of aluminum to steel, brittle intermetallic compounds are formed, which is necessary to control the thickness of these intermetallic compounds to improve welding properties. Using an aluminum-clad layer can effectively reduce the thickness of intermetallic compounds by reducing the heat generation at the steel-aluminum interface. This research aims to investigate experimentally and theoretically the welding of aluminum-clad steel sheet to Al-Mg aluminum sheet by resistance spot welding process with finite element method...
Theoretical and Experimental Investigation of Cold Roll Welding for Production of Aluminum Clad Steel Sheet
, Ph.D. Dissertation Sharif University of Technology ; Karimi Taheri, Ali (Supervisor)
Abstract
Aluminum coated steel sheet is an excellent composite material in which; the strength and economy of steel and durability of aluminum are combined. This material is produced by several methods. However, there are two main technologies to produce aluminized steel sheets: 1) the hot dip method and 2) the aluminum clad method (cold roll welding process). The hot dip method is most widely used for producing the aluminum coated steel. The aluminum coated steel sheet manufactured by this method is believed to be inferior to an aluminum sheet with respect to surface appearance, corrosion resistance and formability of the coated metal. Consequently, the aluminum clad steel method is one of the most...
Experimental Investigation of the Behavior of Squat Composite Corrugated Shear Walls Under In-Plain Shear
,
M.Sc. Thesis
Sharif University of Technology
;
Khalu, Alireza
(Supervisor)
Abstract
The new lateral load resisting system introduced in this dissertation is a kind of squat composite shear wall consisting of a concrete core as filler and two steel corrugated sheets as cover. Reinforced bars are not used in this kind of construction. Load resisting process of the walls is provided by 3 factors: concrete core, steel corrugated covers on both sides of the central core and shear-friction interaction between the core and covers. There is not any specific formula for their design because of their novelty and few researches on this kind of walls and absence of code provisions. In this project, squat composite walls were constructed with dimensions of 106.8×90 (cm2) from corrugated...
Weld orientation effects on the formability of tailor welded thin steel sheets
, Article Thin-Walled Structures ; Volume 149 , April , 2020 ; Darabi, R ; Ghabussi, A ; Habibi, M ; Foong, L. K ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Tailored welded blanks (TWBs) technology can give the important possibilities to obtain components in the automobile industry. Friction stir welding (FSW) is a joining approach, which can adhere parts well with desired properties in weld zone. In this article, the main aim is investigation the effect of weld zone orientation on forming limit diagram (FLD) of the TWBs using experimental and finite element model. Three TWBs are produced FSW with three different orientations of weld zones including 00, 450 and 900 against major stress direction. The microstructure of the weld zones is divided and then observed via metallography procedures. Tensile tests are carried out to determine the...
Welding of Al-Mg aluminum alloy to aluminum clad steel sheet using pulsed gas tungsten arc process
, Article Journal of Manufacturing Processes ; Volume 31 , 2018 , Pages 494-501 ; 15266125 (ISSN) ; Movahedi, M ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
Al-Mg aluminum alloy was lap joined to aluminum clad steel sheet using pulsed gas tungsten arc welding process and Al-Si filler metal. The effects of the welding heat-input were investigated on the joint microstructure and mechanical properties. Weld metal microstructure, formation of intermetallic compounds (IMCs) at the joint interface and the fracture locations were studied using stereo, optical and scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS). The joint strength of the welds was evaluated by shear-tensile test. The results showed that presence of a thin aluminum clad layer with 350 μm thickness drastically decreased the Al-Fe intermetallic...
Vibration based damage detection in smart non-uniform thickness laminated composite beams
, Article TIC-STH'09: 2009 IEEE Toronto International Conference - Science and Technology for Humanity, 26 September 2009 through 27 September 2009, Toronto, ON ; 2009 , Pages 176-181 ; 9781424438785 (ISBN) ; Saeedi, E ; Zabihollah, A ; Ahmadi, R ; Sharif University of Technology
Abstract
Laminated composite beams with non-uniform thickness are being used as primary structural elements in a wide range of advanced engineering applications. Tapered composite structures, formed by terminating some of the plies, create geometry and material discontinuities that act as sources for delamination initiation and propagation. Any small damage or delamination in these structures can progress rapidly without any visible external signs. Due to this reason early detection of damage in these systems during their service life is receiving increasing attention. The presence of a crack in a component or structure leads to changes in its global dynamic characteristics results in decreases in...
The modeling and process analysis of resistance spot welding on galvanized steel sheets used in car body manufacturing
, Article Materials and Design ; Volume 34 , February , 2012 , Pages 759-767 ; 02641275 (ISSN) ; Kolahan, F ; Kokabi, A. H ; Sharif University of Technology
Abstract
In this study, the resistance spot welding (RSW) process of the galvanized interstitial free (IF) steel sheets and galvanized bake hardenable (BH) steel sheets, used in the manufacturing of car bodies, has been modeled and optimized. The quality measure of a resistance spot welding joint is estimated from the tensile-shear strength. Furthermore, four important process parameters, namely welding current (WC), welding time (WT), electrode force (EF), and holding time (HT) are considered as the factors influencing the quality of the joints. In order to develop an accurate relationship between the process inputs (4-component vectors) and the response output (tensile-shears strength) at first a...
The influence of fiber/matrix debonding on inelastic micro-mechanical behavior of cross-ply IMC composites
, Article ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis, ESDA2010, 12 July 2010 through 14 July 2010, Istanbul ; Volume 4 , 2010 , Pages 197-222 ; 9780791849187 (ISBN) ; Abedian, A ; Sharif University of Technology
2010
Abstract
In this study the effect of stress field on delamination and fiber/ matrix debonding in laminated composite panels is investigated from the micro-mechanical point of view by means of 3-D Finite Element Models. Specifically, the behavior of two-layer cross-ply symmetric laminates made up of SCS-6/Ti-24Al-11Nb Intermetallic Matrix Composite (IMC) during cooling from the processing temperature is studied. The results show that large plastic strains occur at the fiber/ matrix interface at the fiber end on the laminate free edge which may eventually extend to the interface of the layers of the laminate inflicting delamination damage. This phenomenon is more serious at the corner areas of the...
The effects of annealing phenomena on the energy absorption of roll-bonded Al-steel sheets during wedge tearing
, Article Materials Science and Engineering A ; Volume 527, Issue 27-28 , 2010 , Pages 7329-7333 ; 09215093 (ISSN) ; Kazeminezhad, M ; Sharif University of Technology
Abstract
The purpose of this paper is to investigate the effects of annealing phenomena on the energy absorption of Al-steel bilayer sheets, bonded by cold rolling, through wedge tearing. Tearing by wedge is a dissipating energy system that includes three components: cutting, friction and plastic deformation due to bending. In order to find the bonding and annealing effects on energy absorption, the non-bonded bilayer sheets are prepared in the same condition of bonded ones. The results show that energy absorption of bonded sheets is larger than that of non-bonded ones. This is due to different plastic bending moment of bonded and non-bonded bilayer sheets. Whenever the bond is improved by heat...
The effect of constrained groove pressing on grain size, dislocation density and electrical resistivity of low carbon steel
, Article Materials and Design ; Volume 32, Issue 6 , 2011 , Pages 3280-3286 ; 02641275 (ISSN) ; Kazeminezhad, M ; Sharif University of Technology
Abstract
In this research, constrained groove pressing (CGP) technique is used for imposing severe plastic deformation (SPD) on the low carbon steel sheets. Using transmission electron microscopy (TEM), X-ray diffraction (XRD) and optical microscopy, the microstructural characteristics of produced sheets are investigated. The results show that CGP process can effectively refine the coarse-grained structure to an ultrafine grain range. Dislocation densities of the ultrafine grained low carbon steel sheets are quantitatively calculated and it is found that the CGP can effectively enhance the dislocation density of the sheets. Measurements of their electrical resistivity values show that microstructure...
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 annealing phenomena and thermal stability of severely deformed steel sheet
, Article Materials Science and Engineering A ; Volume 528, Issue 15 , June , 2011 , Pages 5212-5218 ; 09215093 (ISSN) ; Kazeminezhad, M ; Sharif University of Technology
2011
Abstract
However, there are many works on annealing process of SPDed non-ferrous metals, there are limit works on annealing process of SPDed low carbon steel. Therefore, in this study the annealing responses after constrained groove pressing (CGP) of low carbon steel sheets have been investigated. The sheets are subjected to severe plastic deformation at room temperature by CGP method up to three passes. Nano-structured low carbon steel sheets produced by severe plastic deformation are annealed at temperature range of 100-600 °C for 20. min. The changes of their microstructures after deformation and annealing are studied by optical microscopy. The effects of large strain and annealing temperature on...
Tearing energy of an annealed bilayer sheet through multiple and single tensile tests
, Article Materials Science and Engineering A ; Volume 528, Issue 29-30 , November , 2011 , Pages 8800-8803 ; 09215093 (ISSN) ; Kazeminezhad, M ; Sharif University of Technology
2011
Abstract
Tearing energies of annealed Al-steel bilayer sheets are investigated through multiple and single tensile tests. Total tearing energy of two layers determined separately by single tensile test is equal to tearing energy of bilayer sheet. It means that the bond between two layers has no effect on tearing energy
Resistance spot welding of ultra-fine grained steel sheets produced by constrained groove pressing: Optimization and characterization
, Article Materials Characterization ; Volume 69 , 2012 , Pages 71-83 ; 10445803 (ISSN) ; Kazeminezhad, M ; Kokabi, A. H ; Sharif University of Technology
2012
Abstract
Constrained groove pressing as a severe plastic deformation method is utilized to produce ultra-fine grained low carbon steel sheets. The ultra-fine grained sheets are joined via resistance spot welding process and the characteristics of spot welds are investigated. Resistance spot welding process is optimized for welding of the sheets with different severe deformations and their results are compared with those of as-received samples. The effects of failure mode and expulsion on the performance of ultra-fine grained sheet spot welds have been investigated in the present paper and the welding current and time of resistance spot welding process according to these subjects are optimized....
Resistance spot welding of aluminum to aluminum clad steel sheet: experimental and theoretical analysis
, Article Journal of Manufacturing Processes ; Volume 58 , 2020 , Pages 429-435 ; Movahedi, M ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
In order to increase the cross-tension to the tensile-shear peak load ratio, aluminum clad steel sheet produced by roll bonding, was used for resistance spot welding to Al-Mg aluminum alloy. The results showed that the weld nugget formed between the aluminum clad layer and Al-Mg base sheet was the load bearing area. Presence of the metallurgical bond between the steel sheet and the aluminum clad layer led to the formation of the Al/Fe intermetallic compound with the thickness less than ∼3.5 μm. This narrow intermetallic layer did not play a detrimental role in the weld strength and therefore, the cross-tension to the tensile-shear peak load ratio reached up to ∼0.5 at the maximum...
Relationship between failure behaviour and weld fusion zone attributes of austenitic stainless steel resistance spot welds
, Article Materials Science and Technology ; Volume 24, Issue 12 , 2008 , Pages 1506-1512 ; 02670836 (ISSN) ; Pouranvari, M ; Sanaee, M. H ; Abedi, A ; Abootalebi, H ; Goodarzi, M ; Sharif University of Technology
2008
Abstract
Resistance spot welding was used to join austenitic stainless steel sheets. Mechanical properties of the spot welds were evaluated using tensile shear test. Mechanical behaviour was described by peak load, failure energy and failure mode. The relationship between weld fusion zone attributes and failure behaviour was studied. Generally, it was observed that increasing fusion zone size is accompanied by an increase in load carrying capacity and energy absorption capability. However, when expulsion occurs, despite almost constant weld fusion zone size, energy absorption capability reduces significantly due to increase in electrode indentation depth. Considering the failure location and failure...
Numerical study of shunting effect in three-steel sheets resistance spot welding
, Article International Journal of Engineering, Transactions B: Applications ; Volume 35, Issue 2 , 2022 , Pages 406-416 ; 1728144X (ISSN) ; Farrahi, G. H ; Minaei, M ; Masajedi, R ; Gholamnia, M ; Shademani, M ; Sharif University of Technology
Materials and Energy Research Center
2022
Abstract
The main purpose of the present research is to investigate the shunting phenomenon in a three-sheet RSW joint usingfinite element simulation. To this end, a three-sheet resistance spot weldingjoint was simulatedas an electrical-thermal-mechanical couplingproblem.Tovalidate the presentedsimulation, the finite element results were compared with the experimental results, including nugget size and geometric shapein theresistance spot weldingjoint.Afterwards, the multi-spot welds of three-sheet low carbon steels with the same thicknesses were analyzed considering the sequential distance of 45 mm. Various techniques, includingnewspot-welddiametermeasurement, electrical current density, electrical...
Metallurgical characteristics and failure mode transition for dissimilar resistance spot welds between ultra-fine grained and coarse-grained low carbon steel sheets
, Article Materials Science and Engineering A ; Volume 637 , 2015 , Pages 12-22 ; 09215093 (ISSN) ; Kazeminezhad, M ; Kokabi, A. H ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
We studied the microstructure and mechanical characteristics of spot welded specimens, fabricated from low carbon steel sheets with different microstructures. Both ultra-fine grained (UFG) steel sheet and coarse grained (CG) steel sheet were used. The refined microstructure of the UFG steel has been produced by severe plastic deformation (SPD) using the constrained groove pressing (CGP) method. The grain size of the base metals was approximately 260. nm and 30. μm in diameter, respectively, in the UFG and CG steels. Examining the microstructure of a cross section cut through the spot weld reveals a similar grain size and phase distribution in the nugget on both the sides of the initial...
Mechanical properties and microstructure of resistance spot welded severely deformed low carbon steel
, Article Materials Science and Engineering A ; Volume 529, Issue 1 , 2011 , Pages 237-245 ; 09215093 (ISSN) ; Kazeminezhad, M ; Kokabi, A. H ; Sharif University of Technology
2011
Abstract
The welding of nanostructured low carbon steel sheets produced by severe plastic deformation (SPD) has been considered in the present paper. Constrained groove pressing (CGP) method is used for imposing the severe plastic deformation to the steel sheets as a large pre-strain. The SPDed sheets are joined using resistance spot welding (RSW) process. The results show that severe plastic deformation can effectively increase the electrical resistivity of steel sheets; therefore it can affect the microstructure and mechanical properties of spot welds. Microstructure and mechanical properties of fusion zone, heat affected zone (HAZ), recrystallized zone and base metal of SPDed sheets are...