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Effect of Microalloying Additions on the Microstructure and Mechanical Properties of Low Carbon Steel

Journal of Iron and Steel Research International 2011年第S1期18卷 246-251页

作者： EISSA Mamdouh ABD El-Aziz Ahmed ghali saeed HALFA Hossam SABER Shady Central Metallurgical Research & Development Institute "CMRDI" Faculty of Material Science and Engineering German University in Cairo "GUC"

Low carbon steels are characterized by good weldability,formability and fracture toughness ***,the low strength levels of these steel grades limit their wide *** the other hand,increasing the strength by increasing the carbon content and alloying elements deteriorates the other *** this study,the microalloying technique was used to examine the possibility of attaining low carbon steels with good combination of strength,ductility and impact properties.A low carbon steel microalloyed with single addition of vanadium and another one microalloyed with combined addition of vanadium and titanium were used in this investigation and their properties were compared with non-microalloyed low carbon steel having the same base ***,other two nonmicroalloyed and V-microalloyed steels with higher carbon,silicon and manganese contents were also investigated to reveal the effect of base ***,hardness,room and zero temperature Charpy V-notch impact tests were conducted to evaluate the variations in the mechanical properties of low carbon hot forged steel containing vanadium and combinations of vanadium and *** addition,the microstructures of the different investigated steels were observed using both optical microscope and scanning electron ***,the hardness of the ferrite phase was also determined using micro-hardness *** results showed improvement of the mechanical properties of the investigated steels by both single V-and combined V + ***,hardness and impact tests results indicated that good combinations of strength,ductility and impact properties can be achieved by V-microalloying *** with combination of V and Ti microaddition has much higher hardness,yield strength,ultimate tensile strength and impact energy at both room and zero temperatures compared with non-microalloyed and single Vmicroalloyed *** C,Si and Mn contents result in

关键词： low carbon steels single microalloying combined microalloying strength ductility impact energy grain refinement precipitation strengthening

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A Model for FeSiMg Alloy Production by Reduction Technique

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Journal of Minerals and Materials Characterization and Engineering 2011年第9期10卷 865-874页

作者： saeed Nabil saeed ghali Steel Technology Department Central Metallurgical Reseach & Development Institute (CMRDI) P.O Box 87 Helwan 11722 Egypt.

Ferrosilicon magnesium is basic foundry alloys used for the production of ductile cast iron. Magnesium content plays an important role in the produced alloy grades from dolomite ore. The focus of the present work is to simulate mathematical model to predict magnesium content in the ferrosilicon magnesium, which produced by silicothermic reduction of calcined dolomite. The basic assumptions of this model are: constant low viscosity of molten charge, the reaction is irreversible of second order and the reaction is isothermal. The reaction is based on the following equation: 2MgO+2Si →Mg2Si+SiO2 The results of previous work was found to be in a good coincidence with the predicted values by the model [Mg]=(MgO0)[Si0][eKt[(MgO0)-[Si0]]-1]/ (MgO0)[eKt[(MgO0)-[Si0]]-[Si0]] where [Mg] is the concentration of magnesium metal in ferrosilicon magnesium alloy in mol/L. [Si0] and (MgO0) are the initial concentration of silicon and magnesium oxide in charge in mol/L, while t is time in second, K is the reaction rate constant ( 3.26588x10-7 L Sec-1 mol-1). The predicted values are greater than the experimental values;this may be attributed to the use of concentration instead of the activity. The predicted values of magnesium content in ferrosilicon magnesium alloy are in a good agreement with the experimental results obtained in previous work at low viscosity.

关键词： activity model ferrosilicon magnesium reduction viscosity

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Validation of Calculated Thermal Parameters with Experimental Results in SOFCs

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Journal of Minerals and Materials Characterization and Engineering 2018年第2期6卷 193-202页

作者： saeed ghali Azza Ahmed Taha Mattar Steel Technology Department Central Metallurgical Research & Development Institute (CMRDI) Cairo Egypt

Eleven steel grades were designed to be used as metallic interconnects for Solid Oxide Fuel Cells (SOFC). Low carbon, high chromium steel with different additives of niobium, vanadium, aluminum, molybdenum, silicon, manganese and titanium were produced. Phase transformation temperatures;eutectoid temperature (Ac1) and temperature at which transformation of ferrite to austenite is completed during heating (Ac3) were measured by L75-76 dilatometer. The influence of the alloying elements on transformation temperatures was analyzed using MATLab. Considering the interaction between different alloying elements two equations for predicting Ac1 & Ac3 were obtained. The obtained Ac1 & Ac3 by these equations showed more compatibility than that obtained by traditional ones. In addition, the coefficients of thermal expansion of these steel grades were detected. The influences of chemical composition and temperature on the thermal expansion coefficient were analyzed;the obtained equations were verified to certain extent by using several kinds of steels. The predicted values were in good accordance with the experimental results which proof the validation of calculation model.

关键词： Transformation Temperature Thermal Expansion Coefficient SOFCs Steel Matlab

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Some Features of the Influence of Titanium and Nitrogen Addition to NiCrMoV Steel

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Journal of Minerals and Materials Characterization and Engineering 2018年第2期6卷 203-217页

作者： saeed ghali Mamdouh Eissa Michael Mishreky Steel Technology Department Central Metallurgical Research & Development Institute (CMRDI) Cairo Egypt

This paper reports a study of the addition effects of either titanium or titanium and nitrogen of steel grade DIN 56NiCrMoV7 on mechanical properties. Three steel grades were produced in 30 kg-induction furnace, one conforms the chemical composition of conventional 56NiCrMoV7 while the other two produced steels were microalloyed by either titanium or titanium and nitrogen. The produced cast steel grades were reheated to 1150°C and hold for 2 hours, followed by forging process. The forging process was carried out in temperature range 950°C - 1100°C. Solution treatment of hot forged steels was conducted at 880°C, 850°C followed by air and oil quenching, respectively. Quenched steel samples of different steel grades were tempered at different temperatures in the range of 300°C to 650°C for 45 min. The hardness variations after tempering of the two modified steels comparing with the conventional 56NiCrMoV7 steel were studied. Microadditions of titanium or titanium and nitrogen were found to produce secondary hardening at 550°C to 575°C (45 min) with a hardness peak higher than that attained in the conventional 56NiCrMoV7 steel. The effect of titanium and nitrogen additions on phases formation was investigated by Thermo-Calc. SEM was used to confirm Thermo-Calc analysis. Interpretation between hardness and formed phases has been illustrated.

关键词： Thermo-Calc Tool Steel Vanadium Titanium Nitrogen Secondary Hardening

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Activation Energy of Nitriding Medium Carbon Ferromanganese Alloy

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Journal of Iron and Steel Research International 2013年第1期20卷 58-61,78页

作者： saeed N ghali Mamdouh M Eissa Micheal L Mishreky Steel Technology Department Central Metallurgical Research and Development Institute (CMRDI)Helwan 11421CairoEgypt

Investigation of some kinetics aspects of the reaction between nitrogen and medium carbon ferromanganese （MC-FeMn） was made. Nitriding process of fine medium carbon ferromanganese was carried out at temperature ranging from 973 to 1 223 K and time up to 480 min. Nitriding was carried out under nitrogen and hydrogen gas pressures. At temperature of 573 K, hydrogen gas was injected with pressure of about 0.2 MPa followed by injection of nitrogen gas up to 1.2 MPa. Sample mass was 35 g, nitrided in cylindrical chamber with 34 mm in inner diameter and 1 200 mm in length. The change in nitrogen pressure was taken as an indication for nitrogen pickup. The mass gain i.e. nitrogen pickup in kilograms per surface area （m2） was determined by time at different temperatures. Nitriding rate constants were calculated and the activation energy of nitriding process was derived from Arrhenius equation. The nitriding rate constant was found to be increased by increasing temperature of the reaction. The activation energy of nitriding process of fine medium carbon ferromanganese at time ranging up to 28 800 s is around 140 kJ/mol. It was found that the rate controlling step of the nitriding process of MC-FeMn is diffusion mechanism.

关键词： nitriding ferromanganese gas solid reaction activation energy

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Nitriding of Medium Carbon Ferromanganese Alloy in Gas Solid Reaction

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Journal of Minerals and Materials Characterization and Engineering 2011年第4期10卷 315-322页

作者： saeed N. ghali Central Metallurgical Research & Development Institute CMRDI P. O. Box 87 Helwan Egypt

Nitriding process of medium carbon ferromanganese was carried out in the solid state, on lab and bench scale at temperature range 1023-1323 K using different nitrogen and hydrogen pressures. The influence of H2/N2 gas ratio, temperature and time on nitriding process of fine (-2 mm) medium carbon ferromanganese were investigated. Nitrogen content, in weight percent ranging from 2.1 to 9.7 could be obtained. The optimum temperature and time of nitriding process was found to be 1223 K and 21.6 ks respectively. The results showed that nitrogen content is mainly depending on time and temperature of nitriding process. The comparison between results of lab and bench scale, at optimum conditions, showed good coincidence. At optimum conditions;1223 K, 21.6 ks and at 2/8 of H2/N2, nitrogen content of fine medium carbon ferromanganese was 9.5%.

关键词： Nitriding Gas Solid Reaction

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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

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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

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