Showing 8 results for Boutorabi
M. Goodarzi, S. M. A. Boutorabi, M. A. Safarkhanian,
Volume 6, Issue 3 (Summer 2009 2009)
Abstract
Abstract:In this study, an effort has been made to determine the influence of rotational speed of tool on themicrostructure and hardness values of friction stir welded 2024-T851 aluminum alloy. The microstructure of stir zonein the joints has been investigated. It was found that the particles such as Al6(CuFeMn) particles are broken up duringfriction stir welding, and the degree of break up of these particles in the stir zone increases with increasing rotationalspeed. Since the break up of these particles and the recrystallization of new grains happen simultaneously, the brokenparticles would be placed in the grain boundaries. Moreover, the hardness value in the stir zone increases withincreasing rotational speed
Mr Mohammadtaher Safarzadeh, Mr Seyed Mohammad Ali Boutorabi, Mr Asghar Arab,
Volume 7, Issue 3 (summer 2010 2010)
Abstract
The effects of anodizing condition and post treatment on the growth of nickel nanowires, were investigated. A two-step anodizing process was applied in phosphoric and oxalic acid solution. Nickel electrochemical plating was applied to fill Anodic Aluminum Oxide (AAO) pores. For pore filling enhancement, AAO surfaces were treated by silver predeposition. After electroplating, aluminum and oxide layer of some specimens were removed. The results showed that silver preplating increases the pore filling and as the applied voltage becomes higher, the pores diameter decreases.
M. Sheikholeslami, S. M. A Boutorabi,
Volume 9, Issue 4 (December 2012)
Abstract
In this research the relationship between graphitization ability and the carbon equivalent (CE %) of a cast iron have been investigated. The first series of moulds were cast at CE of 3.2% and pouring temperature of 1350°C. The other moulds were cast at different CE% with varying Si content. The graphitization ability( c ) was calculated using the thermodynamics aspects of graphitization and CE%. The results showed that the graphitization ability increases with an increase in CE% and decrease with pouring temperature.
S. M. Mostafavi Kashani, H. Rhodin, S. M. A. Boutorabi,
Volume 10, Issue 3 (September 2013)
Abstract
The influences of age hardening and HIP (Hot Isostatic Pressing) on the mechanical properties of A356 (Al 7Si 0.6 Mg) casting alloys were studied. Cast bars were homogenized, heated and maintained at a temperature of 540°C for a duration of 2 hours, followed by rapid cooling in a polymeric solution. The castings were age hardened at 180°C for a duration of 4 hours before being subjected to HIP process at pressure of 104 MPa for 2 hours. The results indicated that the age hardening process used improved the tensile properties of A356. The HIP process removed the internal surface-connected porosities and improved the ductility of the samples significantly. Additionally, HIP reduced scattering in the tensile test data
M. H. Goodarzy, H. Arabi, M. A. Boutorabi, S. H. Seyedein, H. Shahrokhi,
Volume 11, Issue 1 (march 2014)
Abstract
Variation in microstructural features of 2024 aluminum alloy plastically deformed by equal channel angular pressing (ECAP) at room temperature, was investigated by X-Ray diffraction in this work. These include dislocation density dislocation characteristic and the cell size of crystalline domains. Dislocations contrast factor was calculated using elastic constants of the alloy such as C 11, C 22 and C 44 . The effect of dislocations contrast factor on the anisotropic strain broadening of diffraction profiles was considered for measuring the microstructural features on the base of the modified Williamson-Hall and Warren-Averbach methods. Results showed that the dislocations density of the solution annealed sample increased from 4.28×10 12m-2 to 2.41×10 14m-2 after one pass of cold ECAP and the fraction of edge dislocations in the solution annealed sample increased from 43% to 74% after deformation. This means that deformation changed the overall dislocations characteristic more to edge dislocations. Also the crystalline cell size of the solution annealed sample decreased from 0.83μm to about 210nm after one pass of ECAP process at room temperature
S. M. M. Shafiei, M. Divandari, S. M. A. Boutorabi, Naghizadeh,
Volume 12, Issue 2 (June 2015)
Abstract
In this work, TiN/TiCN & PN/TiCN multilayer films were deposited by plasma- assisted chemical vapour
deposition (PACVD). Plasma nitriding (PN) and TiN intermediate layer prior to coating leads to appropriate hardness
gradient and it can greatly improve the mechanical properties of the coating. The composition, crystalline structure
and phase of the films were investigated by X-ray diffraction. Atomic force microscopy and scanning electron
microscopy were employed to observe the morphology and structure of the films. The TiCN layer exhibited a columnar
structure. The adhesion force between the film and the tool steel substrate was 30.8 MPa for TiN/TiCN and 25.4 MPa
for PN/TiCN film determined by pull off tests. The hardness of TiN/TiCN film was 12.75 GPa while it was 5.4 GPa for
PN/TiCN film, respectively. The improvement of the adhesion in TiN/TiCN was attributed to a less gradient hardness
configuration. In addition, the mean friction coefficients of the films were about 0.2 for TiN/TiCN and 0.3 for PN/TiCN
film determined by nanoindentation tests.
R. Khoshhal, M. Soltanieh, M. A. Boutorabi,
Volume 13, Issue 1 (March 2016)
Abstract
Al2O3/TiC composites are used as cutting tools for machining gray cast iron and steels. The addition of iron improves the toughness of Al2O3/TiC composites. Ilmenite, aluminum and graphite can be used to produce in-situ Al2O3/TiC–Fe composites. However, the formation mechanism and reaction sequences of this system are not clear enough. Therefore, the present research is designed to determine the reactions mechanism of the first step of reactions that may be occurred between raw materials. In this research, pure ilmenite was synthesized to eliminate the effects of impurities available in the natural ilmenite in the system. The milled and pressed samples, prepared from the synthesized ilmenite, aluminum and graphite mixture with a molar ratio of 1:2:1, were heat treated at 720°C for 48h. In addition, two samples one containing ilmenite and aluminum with a molar ratio of 1:2 and ilmenite and graphite with a molar ratio of 1:1 were heat treated at 720°C for 48h. The final products were analyzed with XRD. It was found that at 720°C, aluminum reacts with FeTiO3, forming Fe, TiO2 and Al2O3. Since the aluminum content used in the mixture was more than the stoichiometry for reaction of ilmenite and aluminum, some unreacted aluminum remains. Therefore, the residual aluminum reacts with the reduced Fe to form Fe2Al5.
A. Kazazi, S. M. Montazeri, S. M. A. Boutorabi,
Volume 17, Issue 4 (December 2020)
Abstract
In the present study, austempering heat treatment was performed on compacted graphite aluminum cast iron with the chemical composition of 4.8%wt Al, 3.2%wt C, 0.81%wt Ni, 0.37%wt Mn, and 0.02%wt Mg. This study aims to investigate the effect of aluminum additions and removal of silicon on the kinetics of austempering transformation of Fe-3.2%C alloy. The cast samples were austenitized at 900 °C for 120 min and the isothermal austempering heat treatment was performed at 200 °C, 300 °C and 400 °C for 5, 30, 60, 120 and 180 minutes, respectively. Kinetics of this transformation was studied by X-Ray diffraction (XRD) analysis. The effect of temperature and time on the microstructure and hardness of the austempered samples was investigated and discussed. The presence of Al was seen to prolonged formation of the carbides from high carbon austenite, and that expanded the process window in the austempering transformation. Besides, the lower bainitic ferrite phase was observed in the austempered samples at 200 °C and 300 °C. Increasing austempering temperature to 400 °C changed the lower bainite to upper bainite structure. The volume fraction of austenite reached its maximum level (34.6 %) after austempering the samples at 400 °C for 30 minutes.
