Metallurgical and Materials Engineering (E-Journal)
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Comparative study on electrochemical corrosion behavior of boronized X52 steel in 1 M HCl and H2SO4 solutions
No full textThis paper investigates the effect of boronizing treatment on the corrosion resistance of API X52 steel. Borides were grown on API X52 steel in a powder mixture containing 5% B4C as a boron source, 5% NaBF4 as an activator, and 90% SiC as diluents for 4 hours at 950 °C. X-ray diffraction (XRD) analysis revealed that the sample's boride layer contains only Fe2B phases. The corrosion behavior of borided and unborided specimens was investigated using the Tafel extrapolation method in 1M HCl and H2SO4 solutions. The results show that borided specimens have better corrosion resistance than unboronized specimens. The formation of layers of protective iron borides reduces the corrodability of the steel in the borided specimens. Boronizing increased the corrosion resistances of X52 steel in HCl and H2SO4 by 23 and 77-fold, respectively
Investigation of microstructure, and mechanical properties of dissimilar high and ultra-high steel welded joints: application for extreme climate conditions
Get PDFThe paper focuses on the technical challenges of producing high-quality welds in modern extreme climate conditions structures, as welds are typically the weakest part of welded structures. Welding is particularly difficult with high-strength and ultra-high-strength steels (HSS-UHSS), which are used in structures to reduce weight. The microstructural compositions and mechanical properties of dissimilar high-strength and ultra-high-strength steels were investigated in this study, which was performed with three different heat inputs (0.8, 1.2, and 1.8 kJ/mm). There was a 2.3Cr, 0.4Si, and 2.8Mn increase on the FGHAZ microstructure of the S960QC side, confirming the temperature increase in that zone. Microhardness results show softening (160 HV5) in the E500 side's fine grain heat-affected zone (FGHAZ). Bending test results show that when the maximum force applied was 4000N, the fracture angle was close to 149°, and that the fracture zone was oriented exclusively in the FGHAZ, which had the higher softening zone. Tensile results show the fracture zone, which was oriented in the E500 side's FGHAZ. It was suggested that a heat input of 1.2 kJ/mm be applied to the weld dissimilar joint of TMCP E500-S960QC, which will be beneficial for extreme climate conditions.
Effect of alkali and silane treatment on water absorption and mechanical properties of sisal fiber reinforced polyester composites
Get PDFThe present work deals with the effect of water absorption on the mechanical properties of untreated, 10% alkali-treated, and 10% alkali plus 1% silane treated sisal fibers (5%, 10%, and 15%) reinforced polyester composites. Hand lay-up was used to create the composite. The samples were prepared in accordance with ASTM standards, and tests for tensile strength, flexural strength, impact strength, and water absorption were performed. An increase in the tensile, flexural and impact strength was observed with an increase in fibre loading for untreated, alkali-treated and alkali plus silane treated sisal fibre reinforced polyester composites without water absorption, the increase being maximum for 10% alkali plus 1% silane treated fibre composite. Water absorption reduces tensile strength while increasing flexural and impact strength in untreated sisal fiber reinforced composites. There is an increase in tensile, flexural, and impact strength with higher fiber loading for 10% alkali-treated and 10% alkali-treated plus 1% silane treated sisal fiber reinforced polyester composites with and without water absorption. The tensile, flexural, and impact strength of alkali plus silane treated fiber is maximum at any given fiber loading, indicating that the alkali plus silane treatment is effective in improving the fiber matrix interface. Water absorption increases with fiber loading in untreated, 10% alkali-treated, and 10% alkali plus 1% silane treated sisal fiber reinforced polyester composites, with the rate being lowest in alkali plus silane treated fiber reinforced composites
Dynamic Assessment Of Fireball Geometry And Heat Flux From Large Scale Gasoline Releases In Storage Installations
Get PDFAccidental release and ignition of gasoline in large storage tanks can result in devastating fireball events with significant thermal consequences. This study presents a dynamic modeling approach to assess fireball behavior and its associated heat flux under large-scale hydrocarbon storage scenarios. Using the Roberts Method, key fireball parameters—such as maximum diameter, duration, burning rate, and surface emitting power—were quantitatively determined for a 7389 m³ gasoline storage tank filled to 65% capacity. A comprehensive analysis was conducted to compute maximum and actual surface emitting power, followed by heat flux estimation at varying distances using view factor theory and atmospheric transmissivity. The fireball reached a diameter of 889.09 meters with a burn duration of 68.98 seconds and a maximum surface emitting power of 333.985 kW/m². Heat flux values exceeded 80 kW/m² within 100 meters, indicating severe thermal hazard zones. These findings serve as critical input for safety zoning, emergency planning, and fire protection design in petroleum storage facilities. The study emphasizes the necessity of predictive modeling tools for identifying high-risk areas and implementing mitigation strategies in flammable liquid storage environments
Effect of feeding flow rate on characteristics of CuInSe2 films prepared by flash evaporation
Get PDFCopper indium selenide CuInSe2 (CISe) is one of the most promising absorber materials in high efficiency heterojunction thin-film solar cells due to its high conversion efficiency and known high stability. This paper describes a simple method for preparing CuInSe2 films from pre-prepared CuInSe2 ingot powder using a flash evaporation method. The primary goal of this work is to investigate the effect of feeding flow rate on CuInSe2 film characteristics. The powder feeding flow rate into the evaporator has been adjusted to control the film growth rate. Structure, composition, morphology, electrical and optical properties have all been studied for films deposited at different feeding flow rates. The results show that varying the feeding flow rate affects film characteristics, and that lower feeding rates yield films with better characteristics, which should be considered in future semiconductor film processing
Numerical investigation of residual stresses in welded joints of cylindrical shell
Get PDFWelded cylinder structures such as pressure vessels and pipes for transportation have been applied in power stations, aerospace, and shipping industries. The study of weld-induced residual stress is vital in predicting the life of welded cylinder vessels. Depending upon the required diameter and length, they are welded by either circumferential welding or longitudinal welding. In the present work, a sequentially coupled thermal, structural analysis is carried out on circumferential and longitudinal butt weld joints of AH-36 cylinder components. The thermal field distribution and subsequent residual stresses during Gas Tungsten Arc Welding (GTAW) are studied. The moving heat source considered for analysis is based upon Goldak’s double ellipsoidal model. The weld-induced axial and hoop stresses are evaluated on both the outer and inner surfaces of the cylinder. The results for circumferential and longitudinal butt weld joints are compared. The magnitude of peak hoop and axial stresses in longitudinal butt weld joints are 45% and 95% higher than in circumferential butt weld joints. The developed analysis model, used to evaluate the thermal histories and residual stresses, is validated with experimental measurements
Investigation on corrosion and wear properties of Al-7075/TiC composites fabricated by stir casting route
Get PDFMetal matrix composites (MMCs) play a crucial role in the aerospace, automotive and mineral processing industries. The properties of aluminum matrix composites (AMC) that are renowned for their high strength, good stiffness and excellent thermal conductivity can be enhanced by incorporating various reinforcements. In this investigation, Al7075 alloy with TiC (3, 6, and 9 wt.%) reinforcements was processed via stir casting. Optical microscope (OM) and scanning electron microscope (SEM) were utilized to study the microstructural changes. The chemical composition and phases were analyzed using energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) respectively. Evaluations were conducted on properties such as hardness, tensile strength, corrosion and wear behavior. On increasing the wt.% of TiC from 3 to 9 wt.%, it was observed that the hardness increased by 11%, the tensile strength increased by 200%, and the wear rate decreased by 50%. The composite containing 9 wt.% TiC had the lowest corrosion resistance
Resonance of mixing energy and energy of elastic deformations during spinodal decomposition and the composition modulation effect in ZnхCd1-ХTe solid solutions
Get PDFThe Cahn-Hilliard equation is adapted to consider the spinodal decomposition of A2B6 semiconductor solid solutions. This approach is used to analyze the process of spinodal decomposition of ZnхCd1-хTe solid solution, which is accompanied by the appearance of the composition modulation effect during its low-temperature synthesis. Numerical simulations of the spinodal decomposition of the ZnхCd1-хTe solid solution are performed. It is shown that micro-variations of the material composition are related by the resonance phenomenon between the excess mixing energy and the energy of elastic strains arising in the inclusions of the new phase, which are coherently conjugated with the initial crystal lattice. It is revealed that such resonance phenomena are most intense when the conditions for the material synthesis are located in close proximity to the spinodal curves on the phase state diagram of the system
Density functional prediction of the structural, elastic, electronic, and thermodynamic properties of the cubic and hexagonal (c, h)-Fe2Hf
Get PDFThe structural, elastic, electrical, and thermodynamic characteristics of Fe2Hf cubic and hexagonal phases with space group Fd-3m and P63/mmc are presented using the generalized gradient approximations. The k-points mesh density and plane-wave energy cut-off accomplish the energy convergence. The computed equilibrium parameters are closer to the theoretical data. The elastic tensor and crystal anisotropy of ultra-incompressible Fe2Hf are computed in a wide pressure range. The isothermal and adiabatic bulk modulus, as well as the heat capacity of Fe2Hf is successfully calculated utilizing the quasi-harmonic Debye Model. The Fd-3m and P63/mmc Fe2Hf structures are stable in the studied pressure range
Thermal aging and catalyst concentration effects on thermo-dynamical and mechanical properties of a polyester fiberglass composite
Get PDFThis work deals with the characterization by physicochemical and mechanical analysis performed on composite polyester fiberglass plates molded by contact and aged in thermo-stated ovens to simulate their deleterious environment of use. The DSC analysis revealed that the catalyst concentration affected the thermal behavior of the composite. Indeed, the addition of a higher catalyst concentration slightly lowered the glass transition temperature. From a mechanical point of view, it was observed that the catalyst addition made the material stiffer. The properties at fracture were also affected by the catalyst concentration and varied irregularly with aging