Search for: metallurgy
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    Mathematical and computational modeling of mold filling and heat transfer in metal casting

    , Article Iranian Journal of Science and Technology, Transaction B: Engineering ; Volume 29, Issue 5 , 2005 , Pages 511-530 ; 03601307 (ISSN) Babaei, R ; Esmaellian, H ; Varahram, N ; Davami, P ; Sharif University of Technology
    In the present study a finite difference method has been developed to model transient fluid flow and heat transfer in metal casting, A single fluid has been selected for modeling the mold filling and the SOLA VOF 3D technique was modified to increase the accuracy and speed of simulation of filling phenomena for shape castings. The model was then evaluated with the experimental methods. Referring to the experimental and simulation results, a good consistency and accuracy of the suggested model are observed. © Shiraz University  

    The role of heat treatment on wear behavior of powder metallurgy low alloy steels

    , Article Materials and Design ; Volume 23, Issue 7 , 2002 , Pages 667-670 ; 02641275 (ISSN) Khorsand, H ; Habibi, S. M ; Yoozbashizadea, H ; Janghorban, K ; Reihani, S. M. S ; Rahmani Seraji, H ; Ashtari, M ; Sharif University of Technology
    Elsevier Ltd  2002
    The influence of manufacturing parameters such as compacting pressure, heat treatment and microstructure on the static and dynamic properties of Fe-1.75 Ni-1.5 Cu-0.5 Mo-0.6 C was investigated. Wear and fatigue tests were carried out on reciprocate wearing and tension compression mode, respectively. The results show that delamination wear mechanism of sintered steel is similar to that of conventional wrought or cast materials. But, in sintered material, open porosity acts as sites of generation and collection of wear debris or formation of subsurface cracks. Wear rate is decreased and fatigue strength is increased by heat treatment. © 2002 Elsevier Science Ltd. All rights reserved  

    Effect of nanoparticle content on the microstructural and mechanical properties of nano-SiC dispersed bulk ultrafine-grained Cu matrix composites [electronic resource]

    , Article Journal of Materials & Design ; December 2013, Volume 52, Pages 881–887 Akbarpour, M. R ; Salahi, E ; Alikhani Hesari, F ; Kim, H. S ; Simchi, A. (Abdolreza) ; Sharif University of Technology
    In this study, the microstructural and mechanical features of monolithic pure Cu and Cu matrix nanocomposites reinforced with three different fractions (2, 4, and 6 vol%) of SiC nanoparticles (n-SiC) fabricated via a combination of high energy mechanical milling and hot pressing techniques were investigated. The fabricated composites exhibited homogeneous distribution of the n-SiC with few porosities. It was found that the grain refinement, the planar features within the grains, and the lattice strains increase with increase in the n-SiC content. The yield and compressive strengths of the nanocomposites were significantly improved with increases in the n-SiC content up to 4 vol%; then they... 

    Modelling the flow behaviour of steel under non-isothermal conditions

    , Article Materials Science and Technology ; Volume 19, Issue 8 , 2003 , Pages 1065-1069 ; 02670836 (ISSN) Serajzadeh, S ; Zebarjad, S. M ; Sharif University of Technology
    A mathematical model is proposed for evaluating flow behaviour under hot deformation conditions. The effects of dynamic recovery and recrystallisation as well as temperature and strain rate variations are considered in the model by means of Bergstrom's approach and the additivity rule for strain. To verify the model, hot compression tests for three grades of steel together with upsetting experiments are carried out. Comparison between experimental and theoretical results confirms the reliability of the model. © 2003 IoM Communications Ltd. Published by Maney for the Institute of Materials, Minerals and Mining  

    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) Alizadeh Sh, M ; 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... 

    Warm compaction of metallic powders

    , Article Advances in Powder Metallurgy: Properties, Processing and Applications ; 2013 , Pages 86-108 ; 9780857094209 (ISBN) Simchi, A ; Nojoomi, A ; Sharif University of Technology
    Warm compaction is a cost saving and effective method for obtaining high performance powder metallurgy (PM) parts. This chapter presents the principles of warm compaction and technical aspects of the process. The green and sintered properties of warm compacted parts are discussed and compared with conventionally (cold) produced compacts. The applications of the process for ferrous and non-ferrous PM parts are presented and future trends are outlined  

    Similar and dissimilar friction-stir welding of an PM aluminum-matrix hybrid nanocomposite and commercial pure aluminum: Microstructure and mechanical properties

    , Article Materials Science and Engineering A ; Volume 666 , 2016 , Pages 225-237 ; 09215093 (ISSN) Khodabakhshi, F ; Simchi, A ; Kokabi, A. H ; Gerlich, A. P ; Sharif University of Technology
    Elsevier Ltd 
    Friction stir welding (FSW) of dissimilar joints has recently attracted great interest for the fabrication of bimetallic and layered composite structures. In this paper, dissimilar joining of an aluminum-matrix hybrid nanocomposite to commercial pure aluminum is reported for the first time. An aluminum hybrid nanocomposite reinforced with Al2O3 (2 vol%; 15 nm) and SiC (2 vol%; 50 nm) nanoparticles was prepared by powder metallurgy routes including mechanical milling and hot powder consolidation techniques. Different joint designs at various ranges of rotational (w) and traverse velocities (v) were evaluated to determine process window for the dissimilar solid-state welding. Macro- and... 

    Evolutions during synthesis of Al-AlN-nanostructured composite powder by mechanical alloying

    , Article Journal of Alloys and Compounds ; Volume 461, Issue 1-2 , 11 August , 2008 , Pages 166-172 ; 09258388 (ISSN) Abdoli, H ; Salahi, E ; Farnoush, H ; Pourazrang, K ; Sharif University of Technology
    High-energy milling technique was used to synthesize Al-10 wt.%AlN-nanostructured composite powder in a planetary ball-mill under argon atmosphere up to 25 h. To show the role of AlN particles, process was conducted for monolithic aluminum. The changes in powder characteristics were investigated by time. Microstructure of powders was studied after different milling times by scanning electron microscope (SEM). The morphological evolutions showed that relative equiaxed powder could be synthesized after 25 h milling. Structural analysis was performed by X-ray diffraction method (XRD) to determine the grain sizes and lattice strain. Furthermore, particle size analysis (PSA) revealed the... 

    The role of powder preparation route on physical and mechanical properties of Cu-rGO bulk nanocomposites

    , Article Materials Today Communications ; Volume 28 , 2021 ; 23524928 (ISSN) Fahimi, N ; Abachi, P ; Sharif University of Technology
    Elsevier Ltd  2021
    To study the effect of the production method on physical and mechanical properties of Cu-rGO nanocomposites, nanocomposite powder samples with rGO content of 0.25–1 wt.% were prepared via combined routes of molecular-level mixing (MLM) and powder metallurgy (PM). Spark plasma sintering (SPS) was applied to consolidate nanocomposite powders with better control on the grain size. According to the specific electrical resistivity measurements, microhardness, and pin-on-disk wear tests, the sample with 0.5 wt.% rGO comprised the best overall properties. For assessment, samples containing 0.5 wt.% rGO were also produced via PM and MLM routes, separately. The physical and mechanical properties of... 

    Effect of sintering temperature on tribological behavior of Ce-TZP/Al2O3-aluminum nanocomposite

    , Article Journal of Composite Materials ; Volume 49, Issue 28 , December , 2015 , Pages 3507-3514 ; 00219983 (ISSN) Bahrami, A ; Soltani, N ; Pech Canul, M. I ; Sharif University of Technology
    SAGE Publications Ltd  2015
    10Ce-TZP/Al2O3 nanoparticles as reinforcement can be a good substitute in aluminum matrix composites prepared through powder metallurgy. In this work, the effects of sintering temperature on the hardness, friction, and wear characteristics of Al-10Ce-TZP/Al2O3 composites have been investigated. Ce-TZP/Al2O3 nanocomposites were synthesized by the aqueous combustion method. About 7 wt% 10Ce-TZP/Al2O3-aluminum composites in the form of cylindrical samples were prepared at the sintering temperatures of 400°C, 450°C, and 500°C under an applied pressure of 600 MPa for 60 min. The experimental results show that the distribution of Ce-TZP/Al2O3 nanocomposite into the metal matrix is homogenous and... 

    Direct metal laser sintering of Fe-C-Cu steel powder

    , Article European Powder Metallurgy Congress and Exhibition, Euro PM 2005, Prague, 2 October 2005 through 5 October 2005 ; Volume 3 , 2005 , Pages 41-47 ; 9781899072187 (ISBN) Simchi, A ; Petzoldt, F ; Pohl, H ; European Powder Metallurgy Association ; Sharif University of Technology
    European Powder Metallurgy Association (EPMA)  2005
    Cu-alloyed sintered steels are one of the main product groups in ferrous powder metallurgy (P/M). To expand the application of P/M technology to different sectors of industry and to create new market, it is believed that rapid prototyping and short serial production of sintered parts for functional testing is important. In the present work, rapid prototyping of sintered Fe-C-Cu steel powders by direct metal laser sintering (DMLS) process was studied. Fe, Fe-0.8%C, Fe-2%Cu, Fe-4%Cu, Fe-0.8%C-2%Cu-0.35%P powders were laser sintered in widely varying conditions. The densification and microstructural features of the sintered parts were evaluated. The results revealed that rapid prototyping of... 

    Investigation of the Effect of Temperature on Wear Behavior of 2024Al and 2024Al-20vol.%SiCp Composite

    , M.Sc. Thesis Sharif University of Technology Mousavi Abarghouie, Mohammad Reza (Author) ; Seyyed Reihani, Morteza (Supervisor)
    In this research, friction and wear behaviors of 2024 Al and 2024 Al-20 vol.% SiC composite -prepared by powder metallurgy method- were investigated in the temperature range 20- 250°C. Dry sliding wear tests were conducted at a constant sliding velocity of 0.5 m/s, an applied load of 20 N, and a sliding distance of 2500m using a pin-on-disc apparatus. Some of the wear tests were carried out with artificially aged specimens in order to determine the aging effects. Worn surfaces and wear debris were also examined by using SEM, EDS and XRD techniques. All specimens showed a transition from mild to severe wear above a critical temperature. In the mild wear regime, the wear rate and the friction... 

    , M.Sc. Thesis Sharif University of Technology Ourang, Mohammad Reza (Author) ; Ekrami, Ali Akbar (Supervisor) ; Seyed Reihani, Morteza (Supervisor)
    In this research, wear behaviors of 6061Al and 6061Al-20 vol% SiC composite -prepared by powder metallurgy method- were investigated in the temperature range 25- 200°C. Dry sliding wear tests were conducted at a constant sliding velocity of 0.34 m/s, an applied load of 20 N and 50N, and a sliding distance of 2450m using a pin-on-disc machine test. Some of the wear tests were carried out with artificially aged specimens in order to determine the aging effects on wear rate of composite. Worn surfaces and wear debris were also examined by using SEM and EDS techniques. Also for determining the effect of age hardening treatment on wear behavior of composite, specimens were solution treated at... 

    On the modeling of the static recrystallization considering the initial grain size effects

    , Article Materials Science and Engineering A ; Volume 486, Issue 1-2 , 2008 , Pages 202-207 ; 09215093 (ISSN) Kazeminezhad, M ; Sharif University of Technology
    Modeling of the static recrystallization in deformed copper specimens with different initial grain sizes is carried out based on a previous dislocation-grain size interaction model and a Monte Carlo simulation. From the dislocation-grain size interaction model, the stored energy of the deformed copper is calculated considering the interaction of the dislocations due to the different initial grain sizes. Then, utilizing the stored energy and Monte Carlo simulation the kinetic of recrystallization and recrystallized grain sizes are obtained. The JMAK plots of the modeling results show that, in conditions of 2D modeling and site-saturated nucleation, the Avrami exponent is 2 ± 0.1. The time for... 

    Manufacturing of multi-functional micro parts by two-component metal injection moulding

    , Article International Journal of Advanced Manufacturing Technology ; Volume 33, Issue 1-2 , 2007 , Pages 176-186 ; 02683768 (ISSN) Imgrund, P ; Rota, A ; Petzoldt, F ; Simchi, A ; Sharif University of Technology
    Several metals and alloys can be used to enhance the mechanical and physical properties of micro parts and components for micromechanical, micro-chemical or sensor applications. Such parts can be produced in series by the powder metallurgical process of micro metal injection moulding (μ-MIM). This paper describes a novel manufacturing route for metallic multi-material micro components, two-component micro metal injection moulding (2C-μ-MIM). Similar to "two-colour" injection moulding of plastics, the process allows the integration of multiple functions in a micro part by simultaneously injecting and joining two materials in one mould. Net-shape parts with solid material interfaces are... 

    Modelling recrystallization kinetics during hot rolling of AA5083

    , Article Journal of Materials Processing Technology ; Volume 184, Issue 1-3 , 2007 , Pages 345-353 ; 09240136 (ISSN) Toloui, M ; Serajzadeh, S ; Sharif University of Technology
    In this work, a mathematical model has been developed to predict distributions of temperature, strain and strain rate during hot rolling as well as the subsequent microstructural changes after hot deformation. For doing so, a 2-D finite element analysis together with a stream function method have been coupled to calculate temperature distribution and velocity field within the rolling metal while the roll force has been estimated, through using an upper bound solution. Also the additivity rule and Avrami-type equation have been employed to predict the kinetics of static recrystallization after hot rolling. The model has been examined on AA5083. Hot rolling experiments have been conducted... 

    A study on flow behavior of A-286 superalloy during hot deformation

    , Article Materials Chemistry and Physics ; Volume 101, Issue 1 , 2007 , Pages 153-157 ; 02540584 (ISSN) Salehi, A. R ; Serajzadeh, S ; Yazdipour, N ; Sharif University of Technology
    The hot deformation behavior of A-286 superalloy has been characterized using hot compression experiments in the temperatures between 1000 and 1100 °C and strain rates varying between 0.001 and 0.1 s-1. In addition, hot workability of this alloy has been analyzed by employing flow-localization parameter. The results show that both kinds of softening mechanism, dynamic recovery and dynamic recrystallization, occur during hot working, where at 1000 °C the main mechanism is dynamic recovery and at higher temperatures and strain rate of 0.001-0.01 s-1 dynamic recrystallization takes place. Calculations demonstrates that this alloy mainly have a good workability for the utilized deformation... 

    Comparison of mechanical and metallurgical properties of hollow and solid forged products

    , Article Journal of Materials Processing Technology ; Volume 178, Issue 1-3 , 2006 , Pages 181-187 ; 09240136 (ISSN) Taherizadeh, A ; Najafizadeh, A ; Shateri, R ; Jonas, J. J ; Sharif University of Technology
    Some mechanical and metallurgical properties of hollow and solid long forged products are compared. The metallurgical properties include such micro- and macro-structural characteristics as the grain size and grain flow patterns. Mechanical evaluation was performed by means of hardness testing. Some theoretical analyses were also carried out. The results indicate that the hollow or mandrel forged products possess better properties. Both the mechanical and metallurgical properties are more uniform and homogeneous through the thickness direction in such products. By contrast, in the solid forged parts, there is a gradient in the micro- and macro-structural properties from the surface to the... 

    Property change during fixtured sintering of NiTi memory alloy

    , Article Materials and Manufacturing Processes ; Volume 21, Issue 1 , 2006 , Pages 87-96 ; 10426914 (ISSN) Sadrnezhaad, S. K ; Lashkari, O ; Sharif University of Technology
    Fixtured sintering of up to 5 hours at 1223 to 1323 K is successfully used to diminish the dimensional change of NiTi memory alloys produced from mixtures of elemental Ni and Ti powders packed and pressed at room temperature under 400, 500, and 600 MPa pressure. The improvements obtained can help near-net-shape technology via powder metallurgy that overcomes the traditional casting problems such as oxygen, nitrogen, hydrogen, and carbon absorption and intermetallic compound precipitation, which lower the workability and the homogeneity of the final alloy. The effects of compaction pressure, sintering time, and sintering temperature on dimensional change, porosity, hardness, and morphology of... 

    Thermal decomposition of nanostructured Aluminum Titanate in an active Al matrix: A novel approach to fabrication of in situ Al/Al2O3-Al3Ti composites

    , Article Materials and Design ; Volume 88 , 2015 , Pages 932-941 ; 02641275 (ISSN) Azarniya, A ; Hosseini, H. R. M ; Jafari, M ; Bagheri, N ; Sharif University of Technology
    Elsevier Ltd  2015
    The thermal decomposition of Aluminum Titanate in exposure to pure Aluminum was examined both in powder and in bulk form. Optical microscopy, FE-SEM, XRD, DSC and TGA examinations were conducted to take the possible chemical reactions between Aluminum Titanate and Al into consideration. It was found that as Aluminum Titanate particles are exposed to Al matrix, the thermal stability of Aluminum Titanate is degraded and its decomposition temperature is reduced from 850°C to 550°C. Also, the chemical reactions between Aluminum Titanate and Al start along the interfaces, and the reaction products, i.e. Al3Ti, Al2O3, TiO2 and O2 gas are left there. A mechanism was suggested to describe the...