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Effect of Mold Hardness on Microstructure and Contraction Porosity in Ductile Cast Iron
, Article Journal of Iron and Steel Research International ; Volume 18, Issue 4 , 2011 , Pages 44-47+67 ; 1006706X (ISSN) ; Amin Ahmadi, B ; Sharif University of Technology
2011
Abstract
The effect of mold hardness on the microstructure of ductile iron and the contraction porosity was investigated. Molds with different hardnesses (0.41, 0.48, 0.55, 0.62 MPa) and a sand mold prepared by Co2 method were used. The influence of silicon content on the induced expansion pressure owing to the formation of graphite was also investigated. The contraction during solidification can be compensated by an induced expansion owing to the graphite relief when the hardness of mold increases; therefore, the possibility of achieving a sound product without using any riser increases
The Investigation of Effective Parameters on Mechanical Properties of MADI
, M.Sc. Thesis Sharif University of Technology ; Davami, Parviz (Supervisor) ; Varahram, Naser (Supervisor)
Abstract
The Machinable Austempered Ductile Iron (MADI), a new group of Austempered Ductile Iron (ADI), has been developed to remove the problems (hardness and cost) of ADI cast iron. MADI is a special kind of ductile iron which has proper machinabilty properties. This kind of ductile iron can be produced using a specific chemical composition and defined heat treatment process. By providing these conditions, the hardness of the cast iron will be in the range of as-cast cast iron. On the other hand, because of the especial production process, the cost of the final shape casting will be lower than ADI cast iron. In the present work, firstly the effect of heat treatment parameters, including the time...
Investigation into microstructure and mechanical properties of heavy section nickel alloyed austempered ductile iron in accordance with austempering parameters
, Article Material Design and Processing Communications ; Volume 3, Issue 4 , 2021 ; 25776576 (ISSN) ; Varahram, N ; Perseh, Y ; Sharif University of Technology
John Wiley and Sons Inc
2021
Abstract
Austempered ductile iron (ADI) is one of the most widely used types of ductile iron produced by austempering heat treatment. ADI heavy section parts are employed in different industries owing to their unique mechanical properties. Cooling rate in thick parts is significantly low, so heavy section ductile iron parts should have an adequate austemperability for preventing pearlite formation in the middle of the casting. In order to achieve the proper austemperability and fully ausferritic structure, alloying elements like nickel are added to the melt. The objective of this work is to study the role of austempering parameters on nickel alloyed ADI specimens fabricated from 75-mm-thick Y-block....
Influence of Mold Preheating and Silicon Content on Microstructure and Casting Properties of Ductile Iron in Permanent Mold
, Article Journal of Iron and Steel Research International ; Volume 18, Issue 3 , 2011 , Pages 34-39 ; 1006706X (ISSN) ; Behnam, A. A ; Sharif University of Technology
2011
Abstract
The effects of the mold preheating and the silicon content of ductile iron on the percentage of carbides, graphite nodule counts and shrinkage volume were investigated. The results showed that the percentage of carbides and the shrinkage volume decreased when the mold preheating increased. The ductile iron with the carbon equivalent of 4.45% and the silicon content of 2.5% without any porosity defects was achieved when the mold preheating was 450 °C. Increasing the silicon content in the range of 2.1%-3.3% led to the increase in graphite nodule count and graphite size and the decrease in percentage of carbides. It is due to the increase in induced expansion pressure during the graphite...
Study on the Kinetics of Enzymatic Biodiesel Production Using Castor Oil
, M.Sc. Thesis Sharif University of Technology ; Varahram, Nasser (Supervisor) ; Ashuri, Hossein (Supervisor)
Abstract
Increasing emissions of greenhouse gases from one hand and decline in the fossile resources of energy on the other hand has raised the motivation of searching for renewable sources. Biodiesel, because of having perfect feature for replacing with petroleum diesel, has been considered as candidate for this purpose. Using enzymatic reaction is one of the methods for biodiesel production. Understanding the kinetics of this reaction is important to achieve higher production rates. In present work, the kinetic of transesterification of castor oil with use of Novozyme 435 (as enzyme) was investigated. Enzymatic biodiesel production is a bi-substrate (oil and alcohol) reaction. Genetic algorithm was...
Effect of heat treatment cycle on the mechanical properties of machinable austempered ductile iron
, Article 24th ASM International Heat Treating Conference and Exposition, Detroit, MI, 17 September 2007 through 19 September 2007 ; 2007 , Pages 323-327 ; 9781604239300 (ISBN) ; Baghersaee, E. N ; Varahram, N ; Rao, M. H ; Rao, G. V. S. N ; Sharif University of Technology
2007
Abstract
ADI have been used for a wide variety of applications in automotive, rail, and heavy engineering industry because of its excellent mechanical properties such as high strength with good ductility, good wear resistance, and good fatigue properties. The properties of austempered ductile iron are dependent on both chemistry and heat treatment, which has lead to invention of MADI (machinable austempered ductile iron). MADI is a new class of ductile iron with superior mechanical property than regular ductile iron with the same machinability characteristic. In this study Different cycle of austempering process (austenitization and austempering cycle) applied Due to the effect of heat treatment...
Effect of Alloying Elements and Heat Treatment on Microstructure and Mechanical Properties of Austempered Ductile Iron by Modulus above 2 Cm
, M.Sc. Thesis Sharif University of Technology ; Varahram, Nasser (Supervisor) ; Ashuri, Hossein (Supervisor)
Abstract
Since its discovery in 1943, the use of ductile iron is increasing continuously, this is due to the combination of various excellent mechanical properties. Excessive amount of research has being carried out to improve the properties. Austempererd ductile iron is the most recent development in this field. The application of this material included to automobile, railway, military, agricultural, mining & construction industries. The newly developed austempered ductile iron is now replacing steel in many fields so it has become very important to various aspects of this material. In this thesis, the effect of alloying elements (copper & nickel) and the austempering process variables on the...
The Effect of Cu and Sn on Fatigue Properties of Pearlitic Ductile Iron
, M.Sc. Thesis Sharif University of Technology ; Varahram, Naser (Supervisor) ; Davami, Parviz (Supervisor)
Abstract
Pearlitic Ductile Iron are being used variously for producing different kinds of components in industry. For producing of Pearlitic structure in some kind of components such as crankshaft, copper and tin are being used. In many cases according to conditions and facilities of the replacement, these two elements normally have been used.Despite the fact that mostly components are influenced by the fatigue, the influence of these two elements on the fatigue properties of the components hasn’t been studied comprehensively.In this research, the influence of the copper and tin alloying elements on the fatigue limit of the Pearlitic Ductile Iron has been studied.The samples of ductile iron with...
Effect of heat treatment cycle on the mechanical properties of machinable austempered ductile iron
, Article 16th International Metallurgical and Materials Conference, METAL 2007, 22 May 2007 through 24 May 2007 ; 2007 ; Baghersaee, N ; Varahram, N ; Hanumantha Rao, M ; Rao, G. V.S. N ; Sharif University of Technology
TANGER spol. s r.o
2007
Abstract
ADI have been used for a wide variety of application in automotive,rail,and heavy engineering industry because of its excellent mechanical properties such as high strength with good ductility,good wear resistance,and good fatigue properties. The properties of austempered ductile iron are dependent on both chemistry and heat treatment, which has lead to invention of MADI (machinable austempered ductile iron). MADI is a new class of ductile iron with superior mechanical property than regular ductile iron with the same machinability characteristic. In this study Different cycles of austempering process (austenitization and austempering cycle) applied Due to the effect of heat treatment cycle on...
As-cast microstructures of aluminium containing ductile cast iron
, Article TMS Annual Meeting, 14 February 2010 through 18 February 2010, Seattle, WA ; 2010 , Pages 37-47 ; 9781617822933 (ISBN) ; Shayesteh Zeraati, A ; Naser Zoshki, H ; Yousef Sani, M. R ; Sharif University of Technology
2010
Abstract
In this paper, the effect of aluminum content on the formation mechanism, volume fraction, morphology and particle size distribution of graphite has been investigated. Addition of aluminum on ductile iron causes some fundamental changes in iron-carbon phase-diagram and as a result, improves the graphite formation during eutectic transformation. The results reveals that aluminum compounds have been formed in the core of graphite nodules, thus aluminum plays an important role in the formation of graphite nodules. Furthermore, it is indicated that an increase in the aluminum content also leads to an increase in the number of graphite nodules and a decrease in the nodules size. By using EPMA,...
Microstructural and mechanical properties (hardness) investigations of Al-alloyed ductile cast iron
, Article Journal of Alloys and Compounds ; Volume 500, Issue 1 , June , 2010 , Pages 129-133 ; 09258388 (ISSN) ; Naser Zoshki, H ; Kiani Rashid, A.R ; Sharif University of Technology
2010
Abstract
Microstructures and hardness of aluminum alloy ductile iron were investigated by SEM, XRD, EPMA and hardness measurement techniques. The results show, increasing the Al-alloying element leads to decrease of free ferrite and carbide, as well as increase in the pearlite volume fraction. It is also has been found that in the higher values of Al, about 85% of the matrix would be pearlite. It is indicated that an increase in the aluminum content also leads to a decrease in the spacing between pearlite layers. XRD results show, in the presence of Al, intermetallic compounds such as Al6Fe, AlFe3C0.5, Fe3Al and FeAl were produced. Furthermore the hardness measurements illustrate that by increasing...
The effect of aluminium content on morphology, size, volume fraction, and number of graphite nodules in ductile cast iron
, Article Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications ; Volume 224, Issue 3 , 2010 , Pages 117-122 ; 14644207 (ISSN) ; Naser Zoshki, H ; Kiani Rashid, A. R ; Yousef Sani, M. R ; Sharif University of Technology
Abstract
The effect of aluminium content on the formation mechanism, volume fraction, morphology, and particle size distribution of graphite has been investigated. Addition of aluminium to ductile iron causes some fundamental changes in iron-carbon phase diagrams and, as a result, improves graphite formation during eutectic transformation. Results reveal that aluminium compounds have been formed in the core of graphite nodules; thus aluminium plays an important role in the formation of graphite nodules. Furthermore, it is indicated that an increase in the aluminium content also leads to an increase in the number of graphite nodules and a decrease in the nodule size. By using electron probe...
Fatigue properties of machinable austempered ductile iron
, Article 16th International Metallurgical and Materials Conference, METAL 2007, 22 May 2007 through 24 May 2007 ; 2007 ; Baghersaee, N ; Varahram, N ; Hanumantha Rao, M ; Sharif University of Technology
TANGER spol. s r.o
2007
Abstract
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...