Search for: ultimate-tensile-strength
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    Effects of hydrogen level and cooling rate on ultimate tensile strength of Al A319 alloy

    , Article Russian Journal of Non-Ferrous Metals ; Vol. 55, issue. 4 , July , 2014 , p. 365-370 ; 10678212 Bahmani, A ; Eisaabadi, G. B ; Davami, P ; Varahram, N ; Shabani, M. O ; Sharif University of Technology
    The present study investigated the effects of initial Hydrogen level and cooling rate on ultimate tensile strength of commercial Al-A319 alloys. Three hydrogen levels (0.01, 0.2, and 0.41 mL/100 grams of melt) and five cooling rate were studied. Total of 45 tensile test bars was prepared (three hydrogen levels × five cooling rate × three repeats). The UTS of the samples was determined though uniaxial tension tests. Furthermore, the microstructures of the samples were studied by standard metallographic technique and image analysis software. Finally the relationship between UTS and microstructurai features—SDAS and fraction of porosity (Fp%)—of the alloys was investigated.Results of tensile... 

    Investigating the Possibility of Elimination of Nickel and Replacement of Copper and Silicon Instead of that in A336 Casting Alloy Used in Automotive Pistons

    , M.Sc. Thesis Sharif University of Technology Ghasemali, Mojtaba (Author) ; Varahram, Naser (Supervisor)
    In this research the effect of Si, Cu and Ni alloying elements on the structure and mechanical properties of the A336 alloy is investigated. Expriments were done in two situations, casting and heat treated and the results for all samples with different amount of alloying elements are compared and the effect of heat treating is also investigated. Results show that with increasing the amount of Si and Cu and decreasing the amount of Ni strength and hardness of the cast alloy are 134 MPa and 65 HB and they increase to 187 MPa and 89 HB in heat treated alloy. The elongation and coefficient of linear expansion are decreased from 2.3% and 21.94 μm/m.K to 1.1% and 21.62 μm/m.K. Also the T6 heat... 

    The effect of Ti on mechanical properties of extruded in-situ Al-15 pct Mg2Si composite

    , Article Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science ; Volume 44, Issue 9 , September , 2013 , Pages 4366-4373 ; 10735623 (ISSN) Soltani, N ; Bahrami, A ; Pech Canul, M. I ; Sharif University of Technology
    This work was carried out to investigate the effect of different Ti concentrations as a modifying agent on the microstructure and tensile properties of an in-situ Al-15 pctMg2Si composite. Cast, modified, homogenized small ingots were extruded at 753 K (480°C) at the extrusion ratio of 18:1 and ram speed of 1 mm/s. Various techniques including metallography, tensile testing, scanning electron microscopy were used to characterize the mechanical behavior, microstructural observations, fracture mechanisms of this composite. The results showed that 0.5 pctTi addition and homogenizing treatment were highly effective in modifying Mg2Si particles. The results also exhibited that the addition of Ti... 

    Mechanical properties of graphene oxide: A molecular dynamics study

    , Article Fullerenes Nanotubes and Carbon Nanostructures ; Volume 24, Issue 9 , 2016 , Pages 594-603 ; 1536383X (ISSN) Khoei, A. R ; Sarkari Khorrami, M ; Sharif University of Technology
    Taylor and Francis Inc 
    In this paper, the mechanical properties of graphene oxide are obtained using the molecular dynamics analysis, including the ultimate stress, Young modulus, shear modulus and elastic constants, and the results are compared with those of pristine graphene. It is observed that the increase of oxide agents (–O) and (–OH) leads to the increase of C–C bond length at each hexagonal lattice and as a result, alter the mechanical properties of the graphene sheet. It is shown that the elasticity modulus and ultimate tensile strength of graphene oxides (–O) and (–OH) decrease significantly causing the failure behavior of graphene sheet changes from the brittle to ductile. The results of shear loading... 

    Formability of friction stir-welded blanks with different thickness ratios

    , Article Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science ; Volume 47, Issue 5 , 2016 , Pages 2177-2187 ; 10735623 (ISSN) Kolahgar, S ; Ghaffarpour, M ; Habibi, N ; Kokabi, A. H ; Akbarzadeh, A ; Sharif University of Technology
    Springer Boston 
    Welded sheets with different thicknesses are one of the interesting types of tailor-welded blanks (TWBs) that are widely used in metal-forming industries. In the present work, the formability behavior of different 1100-aluminum TWBs was studied. In this regard, the TWBs were made with different thickness ratios by using friction stir welding (FSW) at different welding rotational speeds (ω). The thickness ratios of 1.0, 1.3, and 1.7 were investigated where the thinner sheets had 1.5 mm thick for all conditions; i.e., the volume of welded material increased when the thickness ratio increased. Macrostructural observations, mechanical investigations, and sheet-forming limit tests were... 

    Mechanical and microstructural investigation of friction stir processed Al1100

    , Article Welding in the World ; Volume 53, Issue SPECIAL ISSUE , 2009 , Pages 253-258 ; 00432288 (ISSN) Nasiri, A. M ; Pouraliakbar, H ; Nikravesh, M ; Kokabi, A. H ; Sharif University of Technology
    Surfaces of cast 1100 aluminum were treated by multi-pass friction stir processing (MP-FSP), which is a solid-state microstructural modification technique using frictional heat and stirring action. An improvement in the mechanical properties was accomplished due to the microstructural modification and reduction of porosities. The yield strengths of the MP-FSPed specimens were significantly increased to about 1.4 times versus that of the base metal. The elongation of MP-FSP sample is about 30% higher than that of the base metal. Also the ultimate tensile strength and hardness of MP-FSPed specimens are improved. Moreover the effect of tool rotation rate and tool travel speed on the mechanical... 

    Optimization of mechanical properties of a micro alloyed steel

    , Article Materials and Design ; Volume 30, Issue 6 , 2009 , Pages 2167-2172 ; 02641275 (ISSN) Rasouli, D ; KhamenehAsl, Sh ; Akbarzadeh, A ; Daneshi, G. H ; Sharif University of Technology
    In this work, the effect of hot deformation temperature on microstructure and mechanical properties of micro alloyed steel was studied. The results indicated that by decreasing the deformation temperature final microstructure is refined and the volume fraction of grain boundary ferrite is increased and some pearlite is produced. Therefore both the yield strength and ultimate tensile strength is increased, while the toughness is preserved in comparison to a ferritic-pearlitic microstructure. Also a model was developed to relate the deformation condition to the volume fraction of acicular ferrite at mixed microstructure. © 2008 Elsevier Ltd. All rights reserved  

    A comparative study between friction stir processing and friction stir vibration processing to develop magnesium surface nanocomposites

    , Article International Journal of Minerals, Metallurgy and Materials ; Volume 27, Issue 8 , 2020 , Pages 1133-1146 Bagheri, B ; Abbasi, M ; Abdollahzadeh, A ; Kokabi, A. H ; Sharif University of Technology
    University of Science and Technology Beijing  2020
    Friction stir processing (FSP) can be used to improve surface composites. In this study, a modified method of FSP called friction stir vibration processing (FSVP) was applied to develop a surface composite on AZ91 magnesium alloy. In this technique, the workpiece is vibrated normal to the processing direction. The results illustrated that compared with the FSP method, the FSVP caused a better homogeneous distribution of SiC particles in the microstructure. The results also showed that matrix grains of friction stir vibration processed (FSV-processed) samples ((26.43 ± 2.00) µm) were finer than those of friction stir processed (FS-processed) specimens ((39.43 ± 2.00) µm). The results... 

    Fatigue properties of machinable austempered ductile iron

    , Article 16th International Metallurgical and Materials Conference, METAL 2007, 22 May 2007 through 24 May 2007 ; 2007 Tadayon Saidi, M ; Baghersaee, N ; Varahram, N ; Hanumantha Rao, M ; Sharif University of Technology
    TANGER spol. s r.o  2007
    MADI is new engineering material with very desirable properties such as higher strength at the same hardness compared to regular ductile iron, significantly better fatigue performance than regular ductile iron or austempered ductile iron, better machinability than regular austempered ductile iron and similar to as cast ductile iron. In this study,fatigue properties of Machinable Austempering Ductile was investigated using rotary -bend fatigue testing device. Chemical composition of sample was selected on the base of previous work which results in good mechanical properties and low hardness after austempering process. The results of this study,indicates that for an austempered ductile iron... 

    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 Sarkari Khorrami, M ; Mostafaei, M. A ; Pouraliakbar, H ; Kokabi, A. H ; Sharif University of Technology
    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... 

    Laser welding of NiTi shape memory alloy: Comparison of the similar and dissimilar joints to AISI 304 stainless steel

    , Article Optics and Laser Technology ; Volume 54 , 2013 , Pages 151-158 ; 00303992 (ISSN) Mirshekari, G. R ; Saatchi, A ; Kermanpur, A ; Sadrnezhaad, S. K ; Sharif University of Technology
    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... 

    Microstructure and mechanical property change during FSW and GTAW of Al6061 alloy

    , Article Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science ; Volume 44, Issue 5 , 2013 , Pages 2187-2195 ; 10735623 (ISSN) Fahimpour, V ; Sadrnezhaad, S. K ; Karimzadeh, F ; Sharif University of Technology
    The variation of morphology and mechanical properties of Al6061 automotive aluminum alloy due to friction stir welding (FSW) and gas tungsten arc welding (GTAW) was investigated by optical metallography, scanning electron microscopy, microhardness measurement, X-ray diffraction, tensile testing, and fractography. The center-line dendrite emergence and microhardness reduction in the heat-affected zone were observed in the GTAW process. Although similar microhardness reduction with respect to the base metal was observed in the FSW samples, higher HVs were obtained for the FSW rather than the GTAW process at almost all heat-affected locations. Ultimate tensile strengths of the FSW and the GTAW... 

    Fabrication of aluminium matrix composites reinforced by submicrometre and nanosize Al 2O 3 via accumulative roll bonding

    , Article Materials Science and Technology (United Kingdom) ; 2012 , Pages 1233-1240 ; 02670836 (ISSN) Rezayat, M ; Akbarzadeh, A ; Sharif University of Technology
    Aluminium matrix composites reinforced with submicrometre and nanosize Al 2O 3 particles were successfully manufactured in the form of sheets through eight cycles of accumulative roll bonding process. The mechanical properties of the produced composite are compared with accumulative roll bonded commercially pure aluminium. It is shown that only 1 vol.-% of submicrometre or nanosize alumina particles as reinforcement in the structure can significantly improve the yield and ultimate tensile strengths. Scanning electron microscopy revealed that particles have a random and uniform distribution in the matrix especially in the less volume fraction of alumina particles, and strong mechanical... 

    Ceria reinforced nanocomposite solder foils fabricated by accumulative roll bonding process

    , Article Journal of Materials Science: Materials in Electronics ; Volume 23, Issue 9 , September , 2012 , Pages 1698-1704 ; 09574522 (ISSN) Roshanghias, A ; Kokabi, A. H ; Miyashita, Y ; Mutoh, Y ; Rezayat, M ; Madaah Hosseini, H. R ; Sharif University of Technology
    Springer  2012
    As one of the key technologies for high performance electronic devices, composite solders have been recently developed to improve thermal and mechanical properties of solder joints. In this study, accumulative roll bonding process was used as an effective alternative method for manufacturing high-strength, finely dispersed, void-free and highly uniform Sn-Ag-Cu/CeO 2 nanocomposite solders. Microstructural investigation of nanocomposite solders revealed that homogenous distribution of CeO 2 nanoparticle has been achieved and the eutectic as-cast morphology of the solder changed to recrystallized fine grained structure. As a result of severe plastic deformation during rolling, brittle and... 

    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) Shahriary, M. S ; Koohbor, B ; Ahadi, K ; Ekrami, A ; Khakian Qomi, M ; Izadyar, T ; Sharif University of Technology
    Elsevier  2012
    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... 

    The effect of pre-straining at intermediate temperatures on the mechanical behavior of high-bainite dual phase (HBDP) steels

    , Article Materials Science and Engineering A ; Volume 543 , May , 2012 , Pages 224-230 ; 09215093 (ISSN) Farnoush, H ; Haghshenas Fatmehsari, D ; Ekrami, A ; Sharif University of Technology
    High-bainite dual phase (HBDP) steels with 34. vol.% ferrite were subjected to tensile strains of 1%, 3%, and 5% at intermediate temperatures (150-450. °C). Mechanical behavior of pre-deformed steels was then investigated at room temperature. A maximum value for both yield stress and ultimate tensile strength was observed for pre-deformed steels. A minimum elongation was also found in the same pre-deformed specimens at the range of 250-350. °C. It was found that dynamic strain aging (DSA) plays the major role in mechanical properties of pre-strained HBDP steels. The DSA indicator parameter (DSAP) was introduced to evaluate DSA mechanism. Maxima of DSAP were likewise observed at the range of... 

    Fabrication of porous NiTi alloy via powder metallurgy and its mechanical characterization by shear punch method

    , Article Russian Journal of Non-Ferrous Metals ; Volume 53, Issue 2 , April , 2012 , Pages 169-175 ; 10678212 (ISSN) Parvizi, S ; Hasannaeimi, V ; Saebnoori, E ; Shahrabi, T ; Sadrnezhaad, S. K ; Sharif University of Technology
    In this study, Porous NiTi shape memory alloy has been produced by mechanical alloying of the elemental Ni and Ti powders. The compacting process was done at two temperatures (warm and cold press) and then sintering at 980 and 1050°C was performed on the specimens. Microstructure and mechanical prop-erties of the samples were investigated by optical microscopy, scanning electron microscopy (SEM) and X-ray diffraction. Moreover, shear punch test (SPT) employed to investigate the effect of compaction pressure and sintering temperature on the mechanical properties of the fabricated samples. It was revealed that warm compaction/sintering resulted in 15% yield stress improvement and 20% ultimate... 

    Microstructure, mechanical analysis and optimal selection of 7075 aluminum alloy based composite reinforced with alumina nanoparticles

    , Article Materials Chemistry and Physics ; Vol 178 , August , 2016 , Pages 119–127 ; 02540584 (ISSN) Ezatpour, H. R ; Torabi Parizi, M ; Sajjadi, S. A ; Ebrahimi, G. R ; Chaichi, A ; Sharif University of Technology
    Elsevier Ltd  2016
    Aluminum metal-matrix nanocomposites (AMMNCs) fabricated by conventional stir-casting process usually show high porosity and poor distribution of nanoparticles within the matrix. In the current study, for the improvement of nanoparticles distribution in the aluminum matrix and enhancement of the mechanical properties, a mixture of Al/nano-Al2O3 powders were injected by pure argon gas into the molten 7075 aluminum alloy and this mixture was extruded at high temperature. Mechanical behavior of the final product was investigated by tensile and compression tests, hardness measurements, Scanning Electron Microscopy (SEM), High Resolution Transmission Electron Microscopy (HRTEM) and Optical... 

    In-situ aluminum matrix composite produced by friction stir processing using FE particles

    , Article Materials Science and Engineering A ; Volume 641 , 2015 , Pages 380-390 ; 09215093 (ISSN) Sarkari Khorrami, M ; Samadi, S ; Janghorban, Z ; Movahedi, M ; Sharif University of Technology
    Elsevier Ltd  2015
    In-situ aluminum matrix composites were fabricated by 1-3 passes of friction stir process (FSP) using iron (Fe) particles with initial size of 10. μm. Although the initial reinforcing particles were relatively large in size and also agglomerated particles were formed in the obtained composites, all of the processed specimens fractured from the base metal during transverse tensile test. Longitudinal tensile tests revealed that the ultimate tensile strength (UTS) of the composites was up to 43% higher than that of the base metal; however, the strain to fracture of the composites reached to about 0.2. Al-Fe intermetallic compounds (IMCs) formed at the interface of the aluminum matrix and Fe... 

    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) Molaei, M. J ; Ekrami, A ; Sharif University of Technology
    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