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    Investigation of spring back phenomenon in the 316L stainless steel cathode blank based on the changes in electrical resistivity and magnetic properties due to the residual stress and martensite phase formation: An industrial failure

    , Article Engineering Failure Analysis ; Volume 126 , 2021 ; 13506307 (ISSN) Shojaei, M ; Khayati, G. R ; Hosseini por, H ; Khorasani, S. M. J ; Kafi Hernashki, R ; Sharif University of Technology
    Elsevier Ltd  2021
    316L stainless steel is widely used as cathode blank in copper electrorefining. These cathode blanks become distorted through the cathode stripping in the cathode stripping machine and must be straightened before using again. After several times repeated cold straightening, the cathode blank spring backs to its distorted position during electrorefining resulted in short circuits and current efficiency decreases. The objectives of this study were to: i) investigate the cathode blank spring back behavior and properties; ii) propose a solution adhere to the subject. To achieve these goals, more than 20 samples are selected and cut into small pieces to simulate the cold straightening process.... 

    Phase field approach for nanoscale interactions between crack propagation and phase transformation

    , Article Nanoscale ; Volume 11, Issue 46 , 2019 , Pages 22243-22247 ; 20403364 (ISSN) Jafarzadeh, H ; Levitas, V. I ; Farrahi, G. H ; Javanbakht, M ; Sharif University of Technology
    Royal Society of Chemistry  2019
    The phase field approach (PFA) for the interaction of fracture and martensitic phase transformation (PT) is developed, which includes the change in surface energy during PT and the effect of unexplored scale parameters proportional to the ratio of the widths of the crack surface and the phase interface, both at the nanometer scale. The variation of these two parameters causes unexpected qualitative and quantitative effects: shift of PT away from the crack tip, "wetting" of the crack surface by martensite, change in the structure and geometry of the transformed region, crack trajectory, and process of interfacial damage evolution, as well as transformation toughening. The results suggest... 

    Thermodynamically Consistent Phase Field Modeling of Interaction Between Crack Propagation and Phase Transformation

    , Ph.D. Dissertation Sharif University of Technology Jafarzadeh, Hossein (Author) ; Farrahi, Gholam Hossein (Supervisor) ; Javanbakht, Mahdi (Co-Supervisor)
    According to the widespread application of shape memory alloys, their study in the presence of cracks has received lots of attention in the last two decades. The phase transformation ahead of the crack tip may change the stress field and the fracture behavior, especially at the nanoscale. Thus, modeling this phenomenon helps to recognize the affecting factors on crack propagation and prediction of material behavior when cracks exist. In the first step of this thesis, a phase field approach for crack propagation was presented, first by considering fracture as phase transformation and then as bond breaking. According to the scaling-up strategy, the developed theory is applicable from the... 

    Study of microstructural growth under cyclic martensite phase transition in shape memory alloys; A molecular dynamics approach

    , Article Journal of Intelligent Material Systems and Structures ; 2021 ; 1045389X (ISSN) Moravej, S. A ; Taghibakhshi, A ; Nejat Pishkenari, H ; Arghavani, J ; Sharif University of Technology
    SAGE Publications Ltd  2021
    Shape memory alloys are referred to as a group of alloys that can retrieve the permanent deformation and strain applied to them and eventually return to their original form. So far, various studies have been done to determine the behavior of these alloys under cyclic loading. Most of the studies have mainly been conducted by using the foundations of Continuum Mechanics in order to examine the properties of memory alloys. In this study, instead of using the Continuum Mechanics, a Molecular Dynamics simulation method using Lennard-Jones potential is utilized. The changes in the behavior and properties of memory alloy under cyclic loading are being examined. First, the functional form... 

    Accumulative roll bonding and post-deformation annealing of Cu-Al-Mn shape memory alloy

    , Article Journal of Materials Engineering and Performance ; Vol. 23, issue. 12 , 2014 , pp. 4429-4435 ; ISSN: 1544-1024 Moghaddam, A. O ; Ketabchi, M ; Afrasiabi, Y ; Sharif University of Technology
    Accumulative roll bonding is a severe plastic deformation process used for Cu-Al-Mn shape memory alloy. The main purpose of this study is to investigate the possibility of grain refinement of Cu-9.5Al-8.2Mn (in wt.%) shape memory alloy using accumulative roll bonding and post-deformation annealing. The alloy was successfully subjected to 5 passes of accumulative roll bonding at 600 °C. The microstructure, properties as well as post-deformation annealing of this alloy were investigated by optical microscopy, scanning electron microscopy, x-ray diffraction, differential scanning calorimeter, and bend and tensile testing. The results showed that after 5 passes of ARB at 600 °C, specimens... 

    Effect of carbon content on carbide morphology and mechanical properties of A.R. white cast iron with 10-12% tungsten

    , Article Materials Science and Engineering A ; Volume 542 , April , 2012 , Pages 113-126 ; 09215093 (ISSN) Heydari, D ; Skandani, A. A ; Al Haik, M ; Sharif University of Technology
    Carbide morphologies of white cast iron containing 22% Cr and 10-12% tungsten with different carbon contents (2.34-3.20. wt.%) were investigated. Results indicated that for the as-cast alloys with no heat treatments, the addition of carbon changes the morphology of carbides during air-cooling in the presence of tungsten. Light microscopy analysis revealed that for an alloy with 2.3. wt% carbon, chromium carbides possess coarse gray appearance (GA). Increasing the carbon content reduced the coarse GA zones volume fraction while a finer GA zones emerged. The coexistence of coarse and fine GA phases came to an end at 2.8. wt% carbon, at which only fine GA zones spread throughout the chromium... 

    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) Fallahi, A ; Khamedi, R ; Sharif University of Technology
    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... 

    Nanostructural study of NiTi–TiO2–C core–shell nanoparticles generated by spark discharge method

    , Article Applied Physics A: Materials Science and Processing ; Volume 124, Issue 9 , 2018 ; 09478396 (ISSN) Arzi, M ; Sabzehparvar, M ; Sadrnezhaad, S. K ; Amin, M. H ; Sharif University of Technology
    Springer Verlag  2018
    Abstract: Nickel–titanium (NiTi) nanoparticles are ultrafine smart materials manifesting shape memory effect at very small scales. We have produced NiTi nanoparticles surrounded by an amorphous carbon shell using an innovative spark discharge system. The resulting nanoparticles were studied using various characterization methods to systematically study their size, morphology, size distribution, composition, structure, and thermal behavior. Field-emission scanning electron microscopy and dynamic light-scattering results indicated that the average size of the produced nanoparticles was about 13 nm. High-resolution transmission electron microscopy, energy-dispersive spectroscopy (EDS), and...