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Effect of Layers Position on Fracture Toughness of Functionally Graded Steels in Crack Divider Configuration

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Journal of Materials Science & Technology 2011年第5期27卷 443-452页

作者： Ali Nazari jamshid aghazadeh mohandesi Shadi Riahi Department of Technical and Engineering Sciences Islamic Azad University Department of Mining and Metallurgical Engineering Amirkabir University of Technology

In the present study, fracture toughness of functionally graded steels in crack divider configuration has been modeled. By utilizing plain carbon and austenitic stainless steels slices with various thicknesses and arrangements as electroslag remelting electrodes, functionally graded steels were produced. The fracture toughness of the functionally graded steels in crack divider configuration has been found to depend on the composites＇ type together with the volume fraction and the position of the containing phases. According to the area under stress-strain curve of each layer in the functionally graded steels, a mathematical model has been presented for predicting fracture toughness of composites by using the rule of mixtures. The fracture toughness of each layer has been modified according to the position of that layer where for the edge layers, net plane stress condition was supposed and for the central layers, net plane strain condition was presumed. There is a good agreement between experimental results and those acquired from the analytical model.

关键词： Fracture toughness Modeling Functionally graded steel Crack dividerconfiguration Position of the containing phases

Impact Energy of Functionally Graded Steels with Crack Divider Configuration

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Journal of Materials Science & Technology 2009年第6期25卷 847-852页

作者： Ali Nazari jamshid aghazadeh mohandesi Department of Mining and Metallurgical Engineering Amirkabir University of Technology

Functionally graded steels were produced via electroslag remelting process using the primary electrodes of plain carbon and austenitic stainless steels. Charpy impact energy of as-prepared specimens was measured in the form of crack divider. The obtained results show that the impact energy of the specimens depends on the type and the volume fraction of the present phases. Based on the rule of mixtures, a mathematical model, which correlates the impact energy of functionally graded steels to the impact energy of the individual layers through Vickers microhardness of the layers, was presented. A good compatibility between the experimental results and those obtained from the model was observed.

关键词： Graded steels Impact energy Crack divider Mathematical model

Microstructure and mechanical properties of friction stir weld of dissimilar AZ31-O magnesium alloy to 6061-T6 aluminum alloy

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Transactions of Nonferrous Metals Society of China 2014年第5期24卷 1317-1322页

作者： Alireza MASOUDIAN Arvin TAHAEI Atefeh SHAKIBA Fariborz SHARIFIANJAZI jamshid aghazadeh mohandesi Mining and Metallurgical Engineering Department Amirkabir University of Technology

Dissimilar friction stir welding between AZ31-O Mg and 6061-T6 Al alloys was investigated. 3 mm thick plates of aluminum and magnesium were used. Friction stir welding operations were performed at different rotation and travel speeds. The rotation speeds varied from 600 to 1400 r/min, and the travel speed varied from 20 to 60 mm/min. Defect-free weld was obtained with a rotation speed of 1000 r/min and travel speed of 40 mm/min. Metallographic studies showed that the grain size in the stir zone is much finer than that in the base metals. Complex flow pattern was formed in the stir zone. Microhardness measurement revealed an uneven distribution in the stir zone. Tensile test results indicated that the tensile strength of the welded specimen is about 76% of AZ31 Mg alloy and 60% of the 6061 Al alloy in tensile strength. SEM fracture surface image of the welded specimen indicated that the welded specimen failed through brittle-mode fracture.

关键词： dissimilar frictions stir welding AZ31-O Mg Alloy 6061 Al alloy microstrueture mechanical properties

Characterization， wear behavior and biocompatibility of HA/Ti composite and functionally graded coatings deposited on a Ti-6Al-4V substrate by a mechanical coating technique

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Transactions of Nonferrous Metals Society of China 2023年

作者： Mahmood JALALI BIDAKHAVIDI Hamid OMIDVAR Ali ZAMANIAN jamshid aghazadeh mohandesi Hamid JALALI School of Dentistry，Tehran University of Medical Sciences Department of Materials and Metallurgical Engineering，Amirkabir University of Technology (Tehran Polytechnic) Department of Nanotechnology and Advanced Materials，Materials and Energy Research Center

In this study， characterization， wear behavior， and biocompatibility of HA/Ti composite and functionally graded coatings (FGCs) deposited on a Ti-6Al-4V substrate by a mechanical coating technique were compared. The composite coating was produced using the initial powder mixture of 50Wt% Ti/50Wt% HA， while the FGC was deposited by two separate layers containing 75Wt%Ti/25Wt% HA and 25Wt% Ti/75Wt% HA， respectively. The XRD results exhibited no phase changes during the deposition process. Moreover， due to the presence of Ti particles in the primary powder mixtures， a continuous interface with a superior bond was formed between the coating and the substrate， especially in the samples coated by the FGCs. The wear test results of the non-graded composite coating showed a coefficient of friction (COF) of about 0.37 with an abrupt change at the interface， while the COF of the FGCs increased from 0.32 to 0.5 with a gentle change at the interface. The SEM images of the worn surfaces indicated the dominance of the abrasive wear mechanism. The biocompatibility evaluations revealed better cell attachment and proliferation of the FGC-coated samples.

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Optimization of Mechanical and Wear Properties of Functionally Graded Al6061/SiC Nanocomposites Produced by Friction Stir Processing(FSP)

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Acta Metallurgica Sinica(English Letters) 2015年第5期28卷 584-590页

作者： M.Saadatmand J.aghazadeh mohandesi Department of Mining and Metallurgical Engineering Amir Kabir University of Technology

The objective of present work is to apply the friction stir processing （FSP） to fabricate functionally graded SiC particulate reinforced Al6061 composite and investigate the effect of SiC particle mass fraction distribution on the mechanical properties and wear behavior ofAl6061/SiC composite. Regarding the obtained results in this work, with increasing SiC mass fraction, elongation decreased, but hardness enhanced. However, the optimized functionally graded composite with the highest tensile strength and wear resistance was achieved for composite with 10 wt% surface SiC. Also, the results showed that wear resistance and tensile strength decreased for composite with 13 wt% surface SiC, due to reinforcement particle clustering depending on high SiC mass fraction.

关键词： Functionally graded composite Wear Mechanical properties Friction stir processing (FSP)

A model to determine hole spacing in the rock fracture process by non-explosive expansion material

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International Journal of Minerals,Metallurgy and Materials 2011年第5期18卷 509-514页

作者： Shobeir Arshadnejad Kamran Goshtasbi jamshid aghazadeh Department of Mining Engineering Mahallat BranchIslamic Azad UniversityMahallat ***Iran Department of Mining Engineering Tarbiat Modares UniversityTehran 14115-143Iran Department of Mining and Metallurgical Engineering Amirkabir University of TechnologyTehran ***Iran

The application of the non-explosive expansion material （NEEM） is widely used as the controlled fracture method in quarry min- ing, especially in hard rocks. The pressure of NEEM is an important parameter in causing rock fracture. An empirical model based on hole spacing was developed to determine the pressure of NEEM in the rock fracture process. Primarily, the empirical model was developed by the mathematical method, utilizing dimensional analysis. Then, the Phase2 code, which is based on the finite element method, was utilized to predict crack growth in rocks. The results of numerical analysis show slight deviations from the empirical model. Hence, the polynomial re- gression analysis was used to modify the model. Finally, the modified model shows a good agreement with the results gained from numerical modeling.

关键词： rock fracture dimensional analysis finite element method non-explosive quarry mining

Optimization of process parameters for producing AA6061/SiC nanocomposites by friction stir processing

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Transactions of Nonferrous Metals Society of China 2012年第5期22卷 1055-1063页

作者： M. SALEHI M. SAADATMAND J. aghazadeh mohandesi Department of Mining and Metallurgical Engineering Amir Kabir University of Technology Hafez Ave Tehran Iran

Design of experiment （DOE） was applied to determining the most important factors which influence ultimate tensile strength （UTS） of AA6061/SiC nanocomposites produced by friction stir processing （FSP）. Effect of four factors, including rotational speed, transverse speed, tool penetration depth and pin profile, on UTS, was investigated. By Taguchi method, the optimum of process parameters were determined. Analysis of variance shows that the rotational speed is the most influential parameter. The statistical results depict that UTS for threaded pin is larger than that for square pin. Also, the higher the rotational speed and the lower the transverse speed, the higher the UTS.

关键词： AA6061/SiC nanocomposites Taguchi parametric design approach friction stir processing analysis of variance