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Dry Sliding Oxidative Wear in Plain Carbon Dual Phase Steel

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Journal of Iron and Steel Research International 2007年第4期14卷 43-48页

作者： V Abouei H Saghafian sh kheirandish Department of Metallurgy and Materials Engineering Iran University of Science and TechnologyNarmak 16844TehranIran

To investigate the tribological potential of the dual phase （DP） steel as a wear resistant material, the wear and the friction characteristics of this steel, which consists of hard martensite islands embedded in a ductile ferrite matrix, have been investigated and compared with those observed in plain carbon hardened （H） steel that has the same carbon content of 0.2%. Dry sliding wear tests have been carried out using a pin-on-disk wear testing machine at different normal loads of 21.3 N, 28. 5 N, 35.7 N, and 42.6 N and at a constant sliding velocity of 1.20 m/s. The analysis of surface and wear debris of samples showed that the wear mechanism was mainly mild oxidative. The friction and the wear rate of the H steel and the DP Steel have been explained with respect to the microstructure and the wear mechanism.

关键词： dual phase steel wear microstructure heat treatment

Effects of Silicon Content and Intercritical Annealing on Manganese Partitioning in Dual Phase Steels

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Journal of Iron and Steel Research International 2010年第5期17卷 44-50页

作者： A Nouri H Saghafian sh kheirandish Department of Metallurgy and Materials Engineering Iran University of Science and Technology

Steels of constant manganese and carbon contents with silicon content of 0.34 %- 2.26% were cast. The as-cast steels were then hot rolled at 1 100 ℃ in five passes to reduce the cast ingot thickness from 80 to 4 mm, air cooled to room temperature and cold rolled to 2 mm in thickness. Dual phase microstructures with different volume fraction of martensite were obtained through the intercritical annealing of the steels at different temperatures for 15 min followed by water quenching. In addition to intercritical annealing temperature, silicon content also altered the volume fraction of martensite in dual phase steels. The partitioning of manganese in dual phase silicon steels was investigated using energy-dispersive spectrometer （EDS）. The partitioning coefficient, defined as the ratio of the amounts of alloying element in the austenite to that in the adjacent ferrite, for manganese increased with increasing intercritieal annealing temperature and silicon content of steels. It was also found that the solubility of manganese in ferrite and austenite decreased with increasing intereritical temperature. The results were discussed by the diffusivity and the solubility of manganese in ferrite and austenite existed in dual phase silicon steels.

关键词： partitioning dual phase steel intercritical annealing temperature silicon manganese

Sliding Wear Behavior of a Grey Cast Iron Surface Remelted by TIG

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Journal of Materials Science & Technology 2009年第5期25卷 622-628页

作者： H.Mohamadzadeh H.Saghafian sh.kheirandish Department of Metallurgy and Materials Engineering Iran University of Science and TechnologyTehranIran

The sliding wear behavior of a grey cast iron surface remelted by tungsten inert gas （TIG） was studied and compared with the unremelted one in the current work. To evaluate the wear behavior a Pin-on-Disk wear test machine was used. Pins which were prepared from the samples with the remelted layers of different thicknesses of 1.2, 1.8, 2.5 and 3 turn were worn on an AISID3 steel counterface having a hardness of 63HRC under the applied loads of 54, 76 and gg N at a constant sliding velocity of 0.45 m/s. Scanning electron microscopy （SEM） equipped with energy dispersive X-ray analysis （EDS） and X-ray diffraction （XRD） techniques were used to characterize worn surface and subsurface and also wear debris obtained from the wear tests under different test conditions. Results showed that surface remelted grey cast iron have better wear properties for all applied normal loads in comparison with unremelted ones. Microscopic studies on the worn surfaces and subsurfaces of samples revealed that dominant wear mechanism for surface remelted samples was mild oxidative, while it was severe for unremelted samples. Increasing remelted layer thickness and then forming grosser microstructure lead to a decline of wear properties, whereas lower thickness of remelted layer with finer microstructure due to having higher cooling rate through remelting process can withstand better against wear.

关键词： Grey cast Iron Surface remelted Tungsten inert gas (TIG) Wear

Experimental and numerical study on plasma nitriding of AISI P20 mold steel

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International Journal of Minerals,Metallurgy and Materials 2016年第9期23卷 1065-1075页

作者： N.Nayebpashaee H.Vafaeenezhad sh.kheirandish M.Soltanieh Materials Processing Simulation Laboratory(MPS-LAB) School of Materials and Metallurgical EngineeringIran University of Science and Technology(IUST) School of Materials and Metallurgical Engineering Iran University of Science and Technology(IUST)

In this study, plasma nitriding was used to fabricate a hard protective layer on AISI P20 steel, at three process temperatures（450℃, 500℃, and 550℃） and over a range of time periods（2.5, 5, 7.5, and 10 h）, and at a fixed gas N2：H2 ratio of 75vol%：25vol%. The morphology of samples was studied using optical microscopy and scanning electron microscopy, and the formed phase of each sample was determined by X-ray diffraction. The elemental depth profile was measured by energy dispersive X-ray spectroscopy, wavelength dispersive spectroscopy, and glow dispersive spectroscopy. The hardness profile of the samples was identified, and the microhardness profile from the surface to the sample center was recorded. The results show that ε-nitride is the dominant species after carrying out plasma nitriding in all strategies and that the plasma nitriding process improves the hardness up to more than three times. It is found that as the time and temperature of the process increase, the hardness and hardness depth of the diffusion zone considerably increase. Furthermore, artificial neural networks were used to predict the effects of operational parameters on the mechanical properties of plastic mold steel. The plasma temperature, running time of imposition, and target distance to the sample surface were all used as network inputs; Vickers hardness measurements were given as the output of the model. The model accurately reproduced the experimental outcomes under different operational conditions; therefore, it can be used in the effective simulation of the plasma nitriding process in AISI P20 steel.

关键词： tool steel plasma nitriding sputtering neural networks

The Classification of Filiform Leibniz Superalgebras of Nilindex n+m

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Acta Mathematica Sinica,English Series 2009年第2期25卷 171-190页

作者： sh.A.AYUPOV B.A.OMIROV A.kh.khUDOYBERDIYEV Institute of Mathematics and Information Technologies of Academy Sciences of Uzbekistan Department of Mathematics National University of Uzbekistan

In this work the classification of filiform Leibniz superalgebras of nilindex n ＋ m, where n and m （m≠0） are dimensions of even and odd parts, respectively, is obtained.

关键词： Lie superalgebras Leibniz superalgebras nilpotency characteristic sequence

Effect of Niobium on Microstructure of Cast AISI H13 Hot Work Tool Steel

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Journal of Iron and Steel Research International 2008年第4期15卷 61-66页

作者： shahram kheirandish Ahmad Noorian Department of Material Science and Metallurgical Engineering Iran University of Science and TechnologyTehran 16846-13114 Iran

The effect of niobium addition on the microstructure of cast AISI H13 hot work tool steel was evaluated by using EDX analyzer attached to the scanning electron microscope. The volume percent of eutectic area and eutectic cell size and also volume percent of different carbides of new steel, which is heat treated under different conditions, are also determined. The results show that the a niobium addition modifies the cast structure of Nb-alloyed hot work tool steel, and reduces the size and volume of eutectic cells, and increases the maximum hardness of the steel.

关键词： hot work tool steel H13 niobium NbC microstructure

Effect of Bainite Morphology on Mechanical Properties of the Mixed Bainite-martensite Microstructure in D6AC Steel

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Journal of Materials Science & Technology 2012年第4期28卷 336-342页

作者： khodamorad Abbaszadeh Hassan Saghafian shahram kheirandish School of Metallurgy and Materials Engineering Iran University of Science and Technology Tehran *** Iran

The effect of bainite morphology on mechanical properties of the mixed bainite-martensite microstructure in D6AC low alloy ultra-high strength steel has been studied in the present work. For this purpose, samples austenitized at 910℃ for 40 min were quenched in three different ways. Some of the samples were directly oil-quenched, some others were quenched in salt bath at 330 ℃ and the remaining samples were quenched in salt bath at 425 ℃ for various holding times. All samples were tempered at 200 ℃ for 2 h. Microstructures were examined by optical microscopy （OM） and scanning electron microscopy （SEM）. Fracture surfaces also were studied by SEM. Results showed that the mixed microstructure containing martensite and 28 vol.% of the lower bainite exhibited higher yield and tensile strengths than the fully martensitic microstructure. This could be mainly attributed to the partitioning of the prior austenite grains by the lower bainite and enhancing the strength of lower bainite in the mixed microstructure by plastic constraint. Charpy V-notch （CVN） impact energy and ductility were improved by increasing the volume fraction of the lower bainite. This is not the case about the mixed microstructure containing the upper bainite and martensite. As a result, the tensile and CVN impact properties of mixed upper bainite-martensite microstructure are lower than those of the fully martensitic microstructure. Finally, fractography studies showed cleavage fracture at the surface of CVN impact specimens with martensitic and upper bainitic microstructures confirming the tendency to brittle behavior.

关键词： Upper bainite Lower bainite Microstructure D6AC Mechanical properties

Dry reforming reaction over nickel catalysts supported on nanocrystalline calcium aluminates with different CaO/Al_2O_3 ratios

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Journal of Natural Gas Chemistry 2012年第2期21卷 178-183页

作者： Atiyeh ranjbar Mehran Rezaei Catalyst and Advanced Materials Research Laboratory Chemical Engineering DepartmentFaculty of Engineering University of Kashan Catalyst and Advanced Materials Research Laboratory Chemical Engineering Department Faculty of Engineering University of Kashan Institute of Nanoscience and Nanotechnology University of Kashan

Nanocrystalline calcium aluminates with different CaO/Al2O3 ratios were prepared by a facile co-precipitation method using Poly（ethylene glycol）-block-poly（propylene glycol）-block-poly（ethylene glycol）（PEG-PPG-PEG, MW： 5800） as a surfactant. They were employed as catalyst support for nickel catalysts in methane reforming with carbon dioxide. The prepared samples were characterized by X-ray diffraction （XRD）, N2 adsorption （BET）, temperature-programmed reduction and oxidation （TPR-TPO）, and scanning electron microscopy （SEM） techniques. Catalysts showed a relatively high catalytic activity and stability. TPR analysis revealed that the catalysts with higher CaO content are more difficult to be reduced. TPO analysis showed that the 5 wt%Ni/CA and 5 wt%Ni/C12A7 catalysts with higher CaO amount were effective against coke deposition.

关键词： calcium aluminate nickel catalyst dry reforming

Numerical simulation of benzene transport in shoreline groundwater affected by tides under different conditions

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Frontiers of Environmental Science & Engineering 2022年第5期16卷 83-95页

作者： Mahsa kheirandish Chunjiang An Zhi Chen Xiaolong Geng Michel Boufadel Department of Building Civil and Environmental EngineeringConcordia UniversityMontrealQC H3G 1M8Canada Center for Natural Resources Department of Civil and Environmental EngineeringNew Jersey Institute of TechnologyNewark NJ 07102USA

The release and transport of benzene in coastal aquifers were investigated in the present *** simulations were implemented using the SEAM3D,coupled with GMS,to study the behavior of benzene in the subsurface of tidally influenced *** transport and fate of the benzene plume were simulated,considering advection,dispersion,sorption,biodegradation,and dissolution on the *** tide amplitudes,aquifer characteristics,and pollutant release locations were *** was found that the tide amplitude,hydraulic conductivity,and longitudinal dispersivity were the primary factors affecting the fate and transport of *** tidal amplitude influenced the transport speed and percentage of biodegradation of benzene plume in the beach.A high tidal range reduced the spreading area and enhanced the rate of benzene *** conductivity had an impact on plume residence time and the percentage of contaminant *** hydraulic conductivity induced longer residence time in each beach portion and a higher percentage of biodegradation on the *** plume dispersed and the concentration decreased due to high longitudinal *** results can be used to support future risk assessment and management for the shorelines impacted by spill and leaking *** the heterogeneous beach aquifer subjected to tides can also be further explored in the future study.

关键词： Numerical simulation Benzene Transport and fate shoreline Groundwater Tide