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Effect of cooling rate and composition on microstructure and mechanical properties of ultrahigh-strength steels

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Journal of Iron and Steel Research International 2019年第12期26卷 1350-1365页

作者： Mohammed Ali David Porter Jukka Komi Mamdouh Eissa hoda el faramawy Taha Mattar Materials and Mechanical Engineering Centre for Advanced Steels ResearchUniversity of OuluOulu 90014Finland Steel Technology Department Central Metallurgical Research and Development InstituteHelwanCairo 11421Egypt

The influence of cooling rate on the microstructure and mechanical properties of two new ultrahigh-strength steels(UHSSs)with different levels of C,Cr and Ni has been evaluated for the as-cooled and untempered *** UHSS had higher contents of C and Cr,while the other one had a higher Ni *** the basis of dilatation curves,microstructures,macrohardness and microhardness,continuous cooling transformation diagrams were constructed as a guide to heat treatment *** rates(CRs)of 60,1 and 0.01°C/s were selected for more detailed *** characterization was made by laser scanning confocal microscopy,field emission scanning electron microscopy combined with electron backscatter diffraction,electron probe microanalysis and X-ray *** properties were characterized using macrohardness,tensile and Charpy V-notch impact *** with the higher C and Cr contents showed lower transformation temperatures and slower bainite formation kinetics than that with the higher Ni *** cooling rates led to lower volume fractions and carbon contents of retained austenite together with finer prior austenite grain size,as well as effective final grain size and lath *** changes were accompanied by higher yield and tensile *** best combinations of strength and toughness were obtained with martensitic microstructures and by avoiding the formation of granular bainite accompanied by proeutectoid carbides at low *** the cooling rates studied,UHSS with the higher C and Cr contents showed the higher hardness and strength but at the cost of toughness.

关键词： Ultrahigh-strength steel electroslag remelting Continuous cooling transformation diagram Microstructure feature Mechanical property

Parameters Affecting the Production of High Carbon Ferromanganese in Closed Submerged Arc Furnace

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Journal of Minerals and Materials Characterization and Engineering 2012年第1期11卷 1-20页

作者： Mamdouh Eissa hoda el-faramawy Azza Ahmed Saeed Nabil Hossam Halfa Steel and Ferroalloys Department Central Metallurgical Research and Development Institute (CMRDI) P. O. Box 87 Helwan Cairo Egypt

This study has been performed to investigate the different parameters affecting on the production of high carbon ferromanganese in closed submerged arc furnace. The analysis of industrial data revealed that using manganese ores with low Mn/Fe ratio necessitates higher amount of Mn-sinter in the charge. Using Mn-blend with higher Mn/Fe ratio reduces the coke consumption and this leads to reducing the electrodes consumption. The recovery of Mn ranges between 70 and 80 %. Much higher basic slag has slight effect on Mn- recovery. However, as slag basicity increases, the MnO- content of slag decreases. The manganese content of produced HCFeMn depends mainly on Mn/Fe ratio of Mn-blend. For obtaining HCFeMn alloy containing minimum 75%Mn, it is necessary to use Mn-blend with Mn/Fe ratio of higher than 6. A model for determination of the amount and composition of off-gases has been derived based on the chemical composition and material balance of the input raw materials and the produced alloy and slag. By using this model, the amount of off-gases was found to increase by increasing both Mn-blend and coke consumption.

关键词： Ferromanganese closed Furnaces carbothermic reduction Slag basicity

Influence of Boron Additions on Mechanical Properties of Carbon Steel

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Journal of Minerals and Materials Characterization and Engineering 2012年第10期11卷 995-999页

作者： Saeed N. Ghali hoda S. el-faramawy Mamdouh M. Eissa Steel Technology Department Central Metallurgical Research & Development Institute (CMRDI) Helwan Cairo Egypt

This work aims at the development of carbon steel AISI 1536 through the microalloying addition of boron. Three grades of this steel with different content of boron up to 0.0055% were melted in 100 kg induction furnace. The pro- duced steels were hardened at 960°C for 30 min., followed by tempering at different temperatures and durations. All hardened steels have martensite phase as illustrated with microstructures and X-ray diffraction. Hardness of all tem- pered steel samples was measured to calculate the activation energies of carbon migration through martensite phase. The results indicated that the activation energies of carbon migration through martensite phase decreases with the in- crease of boron content due to its positive effect on the crystallinity of martensite phase. Also, the results showed that the addition of boron up to 0.0023% can improve the steel properties at the lowest temperature and tempered time.

关键词： Boron Steel Microalloy Activation Energy Carbon Migration Martensite

Characterization of Egyptian Manganese Ores for Production of High Carbon Ferromanganese

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Journal of Minerals and Materials Characterization and Engineering 2013年第2期1卷 68-74页

作者： Mohammed Salah Fahim hoda el faramawy Azza Mohammed Ahmed Saaed Nabil Ghali Abd el Hakim Taha Kandil Department of Chemistry Faculty of Science Helwan University Cairo Egypt Department of Steel and Ferroalloys Technology Central Metallurgical Research and Development Institute (CMRDI) Cairo Egypt

This work aims at studying the reactivity of Egyptian manganese ores to be used in the production of ferromanganese alloys in submerged electric arc furnace. Ores with different manganese content (high-medium and low) were selected and characterized by X-Ray Fluorescence (XRF), X-Ray Diffraction (XRD) and Scanning electron Microscope (SEM). The main mineralogical compositions in the three ores are pyrolusite (MnO2) and hematite (Fe2O3). Porosity of selected Mn ores was determined. The reactivity of the different ores was carried out through pre-reduction of the selected ores using thermobalance at 900°C and 1100°C and mixture of CO and CO2 gases. The reduction process was done until steady weight. The reduced ores were examined using XRD and SEM. The results showed that pyrolusite in high and medium ores are converted completely to MnO at 1100°C. However, the ore with low manganese content was converted to MnO and Mn3O4. Consequently, it is clear from the results that Mn ores with high and medium MnO2 content are more reactive than those with low MnO2. Therefore, high MnO2 content Mn ores are preferable to get good economic impact during the production of high carbon ferromanganese.

关键词： High Carbon Ferromanganese Manganese Ores Ore Reactivity CO Reduction Porosity

Effect of Titanium Addition on Behavior of Medium Carbon Steel

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Journal of Minerals and Materials Characterization and Engineering 2012年第11期11卷 1108-1112页

作者： hoda S. el-faramawy Saeed N. Ghali Mamdouh M. Eissa Steel Technology Department Central Metallurgical R & D Institute (CMRDI) Cairo Egypt

This work aims at investigating the influence of titanium addition on behavior of medium carbon steel. Three types of medium carbon steel with different titanium content and one reference steel titanium free were produced in 100 kg induction furnace. Titanium addition was increased up to 0.230%. The produced steels were forged at start temperature 1150°C. Forging process was finished at temperatures 900°C, 975°C, and 1050°C. Microstructure examination and hardness measurement were carried out for forged steels. Mechanical properties and impact measurements were carried out for quenched tempered steels. Ti addition was found to have significant influence on refinement of grains and increase of ferrite/pearlite ratio. It was also, observed that grain size decreases as finishing temperature of forging process decreases. Both Ti addition and lowering finishing forging temperature have positive effect on hardness. In addition, results indicated that addition of titanium has significant effect on the mechanical properties and toughness.

关键词： Titanium Refinement Ferrite Pearlite Forging

electroslag Refining of CrNiMoWMnV Ultrahigh-Strength Steel

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Journal of Minerals and Materials Characterization and Engineering 2017年第6期5卷 385-407页

作者： Mohammed Ali Mamdouh Eissa hoda el faramawy David Porter Jukka Kö mi M. F. el-Shahat Taha Mattar Materials Engineering and Production Technology University of Oulu Oulu Finland Steel Technology Department Central Metallurgical Research and Development Institute Cairo Egypt Chemistry Department Ain Shams University Cairo Egypt

Increasing demands for ultrahigh-strength steels in commercial as well as military applications have raised interest in finding alternatives to the high-cost high-alloyed steel and super-alloys currently used, e.g. the use of economic low-alloy compositions processed via low-cost air induction melting and electroslag refining (ESR). In this work the yield of alloying elements and the removal of the impurities nitrogen, sulphur and phosphorus as a result of electroslag refining (ESR) in a newly developed CrNiMoWMnV ultrahigh-strength steel (UHSS) have been studied in relation to their activities in the molten metal pool. Six experimental heats of CrNiMoWMnV UHSS with different chemical compositions were designed, melted in an induction furnace (IF) and refined using ESR. This was followed by hot forging of the ingots at 1100°C to 950°C. ESR using a CaF2-CaO-Al2O3 slag system led to a high yield in Cr, Ni, Mo, W, Mn and V, while the yield of Si is low. The desulphurization of all six UHSS grades was pronounced with most of the sulphur removed either to the slag or by gas reactions. The degree of dephosphorization was only 5% irrespective of the steel composition. On the other hand, denitrification (removal of nitrogen) was achieved. It ranged from 8% to 63% depending on the steel composition. The yield of the alloying elements and removal of impurities from the steel during ESR depends on the chemical and physical properties of the ESR slag and the activity of the elements in the molten state, taking into account elemental interactions.

关键词： Ultrahigh-Strength Steel electroslag Refining Alloying elements Impurities Activity

Suitability of SDN and MEC to facilitate digital twin communication over LTE-A

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Digital Communications and Networks 2024年第2期10卷 347-354页

作者： Hikmat Adhami Mohammad Alja’afreh Mohamed hoda Jiaqi Zhao Yong Zhou Abdulmotaleb el Saddik Mohamed bin Zayed University of Artificial Intelligence Masdar CityAbu DhabiUnited Arab Emirates School of Computer Science and Technology China University of Mining and TechnologyXuzhou221116China School of electrical Engineering and Computer Science University of OttawaOttawaONK1N 6N5Canada

Haptic is the modality that complements traditional multimedia,i.e.,audiovisual,to evolve the next wave of innovation at which the Internet data stream can be exchanged to enable remote skills and control *** will require ultra-low latency and ultra-high reliability to evolve the mobile experience into the era of Digital Twin and Tactile *** the 5th generation of mobile networks is not yet widely deployed,Long-Term Evolution(LTE-A)latency remains much higher than the 1 ms requirement for the Tactile Internet and therefore the Digital *** work investigates an interesting solution based on the incorporation of Software-defined networking(SDN)and Multi-access Mobile Edge Computing(MEC)technologies in an LTE-A network,to deliver future multimedia applications over the Tactile Internet while overcoming the QoS *** network scenarios were designed and simulated using Riverbed modeler and the performance was evaluated using several time-related Key Performance Indicators(KPIs)such as throughput,End-2-End(E2E)delay,and *** best scenario possible is clearly the one integrating MEC and SDN approaches,where the overall delay,jitter,and throughput for haptics-attained 2 ms,0.01 ms,and 1000 packets per *** results obtained give clear evidence that the integration of,both SDN and MEC,in LTE-A indicates performance improvement,and fulfills the standard requirements in terms of the above KPIs,for realizing a Digital Twin/Tactile Internet-based system.

关键词： LTE-A 5G Digital twin Tactile Internet KPIs SDN MEC NFV Haptic

Childhood asthma biomarkers including zinc: An exploratory crosssectional study

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World Journal of Clinical Pediatrics 2024年第1期13卷 31-40页

作者： hoda Atef Abdelsattar Ibrahim Mona Mohsen Boles Salep Aziz Hanna Dina Mahmoud Khaled Mohamed Abdelhamid el-Khashab Pediatric Clinical Nutrition Unit Faculty of MedicineCairo UniversityCairo 12613Egypt Department of Pediatrics Faculty of MedicineCairo UniversityCairo 12613Egypt Department of Clinical Pathology Faculty of MedicineCairo UniversityCairo 12613Egypt

BACKGROUND Childhood bronchial asthma(BA)is a chronic inflammatory respiratory *** conditions,including zinc deficiency,can affect such allergic *** To outline the difference in serum zinc levels between asthmatic children and healthy *** A cross-sectional study was carried out at Children’s Hospital,Cairo University,investigating serum zinc levels in children with BA(n=40)and healthy children(n=21).Other markers included serum ferritin,iron,hemoglobin(Hb),and immunoglobulin E(IgE)*** t-tests and Mann-Whinny tests were used for *** Kruskal-Wallis test was applied to compare serum ferritin and IgE levels with regard to asthma ***'s rank correlation was performed to explore the relationship between serum ferritin levels and both iron and Hb levels in asthmatic *** Children with BA had higher levels of zinc,yet the difference was not significant(P=0.115).Serum ferritin and IgE levels were significantly higher in asthmatic children(P=0.006 and 0.001,respectively),yet their levels did not differ significantly by severity(P=0.623 and 0.126,respectively).There was a nonsignificant weak correlation between serum ferritin levels and both serum iron and Hb *** Serum zinc levels do not seem to differ between asthmatic children and healthy *** ferritin levels may be a marker of asthma *** IgE levels are not markers of asthma severity.

关键词： Children Asthma Zinc Ferritin

Erratum to:Cadmium nanoclusters in a protein matrix:Synthesis,characterization,and application in targeted drug delivery and cellular imaging

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Nano Research 2024年第6期17卷 5755-5755页

作者： Morteza Sarparast Abolhassan Noori hoda Ilkhani S.Zahra Bathaie Maher F.el-Kady Lisa J.Wang Huong Pham Kristofer L.Marsh Richard B.Kaner Mir F.Mousavi Department of Chemistry Tarbiat Modares UniversityTehran 14115-175Iran Department of Clinical Biochemistry Faculty of Medical SciencesTarbiat Modares UniversityTehran 14115-111Iran Department of Chemistry and Biochemistry University of CaliforniaLos AngelesLos AngelesCA 90095USA Department of Chemistry Faculty of ScienceCairo UniversityGiza 12613Egypt California NanoSystems Institute University of CaliforniaLos AngelesLos AngelesCA 90095USA

The electronic Supplementary Material available online erroneously only contains the first six pages of the entire supplementary material *** will find the entire supplementary material file online linked to this publisher’s *** publisher apologizes to the authors and readers for this *** Supplementary Material:Supplementary material(detailed description on procedures,and further characterizations,including synthesis,optimization,and characterization of CdNCs,HA-CdNCs,and DOX-HA-CdNCs;calculating quantum yield;a Jellium model for assigning the most valid number of the atoms in the NCs;drug loading and release;cellular uptake and cytotoxicity)is available in the online version of this article at https://***/10.1007/s12274-016-1201-z.

关键词： characterization matrix calculating