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Compositional optimization of high induction (> 1.7T) FeCo-based nanocomposite alloys with enhancement of thermo-physical and magnetic properties
No full textThe substitution of Fe with Co and B with Si is investigated in a series of high induction Fe84B13Nb2Cu1 amorphous alloys. The as-quenched melt-spun alloys are structurally amorphous in wheel side and a mild crystallites alongwith amorphous phase in air side. The alloy with 35 at% Co addition depicts improved thermal stability, saturation induction and coercivity, and the optimal combination of soft magnetic properties is achieved for an extended annealing temperature range. The additional 10 at% Si deteriorates soft magnetic properties
Effect of Alloying Elements on Microstructure and Mechanical Properties of Air-Cooled Bainitic Steel
No full textIn the present investigation, a carbide-free bainitic steel has been produced in the laboratory through the air cooling route. Optimization of the alloying elements was done based on thermodynamic and kinetic calculations. Emphasis was given to obtain ultrafine bainitic microstructure by maximizing the driving force and lowering the transformation temperature of bainite formation. In addition to bainite, the microstructure contained a small amount of austenite and martensite. It was observed that Mn decreases ΔGγ → α to a greater extent as compared to Cr and Si. Therefore, a low Mn-high Cr alloy exhibited large driving force and low Bs temperature. Si promoted carbon partitioning in the adjacent austenite to make it more stable. Therefore, the transformation of deformation-induced martensite from the retained austenite during the deformation process was restricted, resulting in higher toughness of the alloy. Thus, the air-cooled bainitic steel produced in lab scale showed better strength, toughness, and hardness than the conventional bainitic steel produced by the isothermal route
Structural evaluation of coking component of West Bokaro coal of Indian origin
No full textDetailed structural elucidation of coal is arduous owing to its complexity and structural heterogeneity. However, an understanding of structural aspect of coking coal is important, in particular, in order to develop structural analogs which could be used as substitutes for metallurgical applications. This study was performed to further corroborate previous structural data gathered for other coking components (CCs) of Indian origin. In the present study, we isolated the CC from West Bokaro coal using density separation followed by organic solvent extraction and performed a detailed structural characterization using XRD, FTIR, Raman, solid-state 13C spectrometry and high-resolution mass spectrometry. The isolated CC has been deduced to possess an ordered graphitic structure comprising of condensed aromatic rings substituted with functional groups like CONH2, OH and SO3H. The presence of graphitic backbone and sulfonic acid group has been found to be in good agreement to previous structural elucidations of Indian coal
Mild pyrolytic treatment of Gmelina arborea for optimum energetic yields
No full textOne of the most promising routes to produce solid biofuel from biomass is mild pyrolytic treatment (torrefaction). In the present study, mild pyrolytic treatment of Gmelina arborea was carried out to obtain optimum energetic yields (mass yield, higher heating value and energy yield). The biomass of 0.5–6 mm particle sizes were torrefied at two different temperatures, 240 and 300°C for residence time of 30 and 60 min. Full-factorial experimental method was used for the optimization of torrefaction conditions in order to produce solid fuel with high energetic yields. The analyses revealed that torrefied biomass was better in terms of heating value, proximate contents and fuel ratio. The results also showed that temperature has the largest effect on the energetic yields compared to residence time and particle size. The optimum torrefaction conditions that produced the highest energetic yields were temperature of 260°C, residence time of 60 min and particle size of 2 mm as predicted using the factorial linear models. The optimum conditions were experimentally validated and the energetic yields obtained were acutely close to those predicted using factorial linear models developed in this study. Hence, mild pyrolytic treatment at a temperature of 260°C, residence time of 60 min and particle size of 2 mm is useful to produce solid biofuel with maximum energetic yields
Thermodynamic Modelling for Design of Synthetic Slag for Inclusion Removal
No full textEnhancement in steel cleanliness is essential for high-performance steels for their high-end applications in structural, automotive, defence and strategic sectors. The non-metallic inclusions play a decisive role in clean steelmaking. The inclusions have to be necessarily minimized or modified by controlling their morphology, composition and size distribution to reduce the detrimental effect of inclusion on the mechanical properties of steel. The present article discusses the results of a thermodynamic study carried out on the various synthetic slags for inclusion removal. It involves computational thermodynamics determining the products of deoxidation, their physical properties and their implication on the quality of steel
Probing true creep-hardening interaction in weld simulated heat affected zone of P91 steels
No full textThe inducement of this paper was to discuss the novel perspective in establishing true creep-hardening interaction at room temperature by hardness and at high temperature by impression creep testing in two boron modified P91 steels. Different sub-heat affected zones(HAZs)were physically simulated. Their creep-strengths were governed by heat treatment,grain-size,hardness,boron addition,and microstructural stability. Post weld heat treatment resulted inreduction in hardness by 50%whereas, impression creep testing showed enhanced creep-strength (50–77%) and the narrow band of creep-damage (∼57%) in P91B steel than P91 steel. An increase in creep-rate with the increase inprior-austenitegra in size show edgra in boundary embrittlement in P91 steel. Whereas, with an increase in creep-rate and the corresponding decrease in prior-austenite grain size show edgra in boundary and sub-grain boundary hardening in P91B steel.Further more,type-IV(fine-grain HAZ) and type-III (coarse-grain HAZ) failures were observed depending upon critical prior-austenite grain size of 17μm in P91 and P91B samples respectively.Based on prior-austenitegra in size and creep-strength,sub-HAZs were classified into different classes pursuant to the nature of creep-damage and discussed systematically.Grain boundary hardening was ineffective for both coarse + finegra in HAZ(CF)and B-CF due to the lock in gmovement of fine-grains.However,the formation of soft ferrite grain sweakens both coarse+inter-critical HAZ(CI) and B-CI.ThisstudyprovidedbetterunderstandingoffailuremechanismsinP91andP91Bsteelsthatresultsin the delay of failures of power plant components
Recovery of Acid and Ferrous Chloride from leach liquor of reduced ilmenite by hydrothermal process
Get PDFIlmenite is the most abundant mineral for the extraction of titanium. It contains more than 50% TiO2 along with iron, silica and alumina. The spinel structure of ilmenite (FeO.TiO2) is so that iron is bounded in the lattice of TiO2 matrix. To remove iron from the ilmenite is a major task for process metallurgists. Various processes have been applied to remove this iron. One of them is reduction and leaching. The carbon containing pellets and environment of jhama coal reduces the iron oxide to metallic state. This metallic iron in then leached in dilute hydrochloric acid (20 vol%) and a greenish color leach liquor is obtained. The pH of the leach liquor solution is found 0.31. This leach liquor contains hydrochloric acid and iron as ferrous chloride. These acid and solid mass was separated by hydrothermal process in the present investigation. The residue containing ferrous chloride was characterized with the help of XRD and EPMA. During experiment it was found that complete separation of HCl and FeCl2 has done. The final pH of separated HCl is found 1.66 and it is suitable for reuse in the leaching of reduced ilmenite and process make a loop. The purity of ferrous chloride is in line with commercial grade which is a sellable product
Evolution of Microstructure in a Low-Si Micro-alloyed Steel Processed Through One-Step Quenching and Partitioning
No full textAn attempt has been made in the current study to investigate the possibility of austenite retention in 0.5 wt pct Si steel without Al, processed through the one-step Q&P technique. The XRD and microstructural analysis confirmed austenite retention (maximum of 5.73 ± 0.16 vol pct), which showed thin film and blocky morphologies. The experimental amount of retained austenite was found to increase with the increasing quench temperature; however, it was almost independent of partitioning time. The carbon content in the retained austenite did not show any significant variation, after Q&P treatment for different time–temperature combinations. The hardness was found to be sensitive to quench temperature than the partitioning time
Solvent Extraction and Separation of Nd, Pr and Dy from Leach Liquor of Waste NdFeB Magnet Using the Nitrate Form of Mextral (R) 336At in the Presence of Aquo-Complexing Agent EDTA
No full textSolvent extraction and separation of Pr, Nd and Dy from a synthetic leach solution of spent NdFeB magnet from wind turbines in the presence of aquo-complexing agent Ethylenediaminetetraacetic acid (EDTA) was studied using the nitrate form of Mextral (R) 336At([336At][NO3]) as an extractant. The effect of different process parameters such as pH, extractant, nitrate, and EDTA concentrations on the extraction of Pr, Nd and Dy was studied. The extraction of these rare earths elements follows the order Pr > Nd > Dy, whereas EDTA forms stable complexes in the order Dy > Nd > Pr. The synergy of these two effects improved the selectivity among these elements as compared to when no aquo-complexing agent was used. The mechanism of extraction of rare earth elements was established by slope analysis method. The Fourier-Transform Infrared Spectroscopy (FTIR) spectra of [336At][NO3] and extracted Nd complex were recorded to understand the interaction of extractant with rare earth metal ions in the organic phase
Influence of microstructure and strain rate on the strain partitioning behaviour of dual phase steels
No full textTwo dual phase steels with varying martensite content (∼ 10 and 33%) have been deformed in tensile mode at various strain rates (0.001–800/s). The microstructural parameters after deformation have been studied in detail using scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). The minute details of deformation features within the ferrite matrix have been investigated using EBSD based misorientation analysis. The influence of metallurgical parameters like ferrite grain size and its spatial distribution, the size and fraction of martensite on the deformation at different strain rates have also been investigated along with evolution of crystallographic texture. It has been found that strain rate influences the gradient in deformation in the ferrite grains between the interface and the grain interiors. Increase in martensite although enhances the dislocation density in the ferrite grains, but it also restricts the rotational ability of ferrite, which led to restricted sub-structural recovery at high strain rates. By observing the misorientation development ahead of the interphase boundaries, the failure mechanisms of these dual phase steels have been explained