This study aims to evaluate the mechanical properties and carry out the metallographic characterization of the butt-welded joints of ASTM A36 steel, with ER70S-6 filler material under the GMAW ...process. It was developed from a quantitative point of view attached to a correlational and experimental approach, through data collection techniques and content analysis. The welding process was based on established parameters such as voltage, amperage, and wire feeding speed, which were then evaluated to develop the experimental process, evaluated properties, and metallographically characterized welded joints. Three plate thicknesses were analyzed, which were welded in various combinations with different parameter values, obtaining four combinations for each thickness. In each of these combinations, ultrasound, traction, face, and root bending tests were carried out. Later, the metallographic analysis was carried out based on three analysis zones: fusion zone, heataffected zone, and base-metal zone, in addition to this, the width of the heat-affected zone, the grain size, and the hardness were also analyzed. Based on the above, five combinations were identified whose beads presented good properties, 250 IPM combinations being the most outstanding. These combinations presented good weldability in the three thicknesses considered, despite having different voltage and amperage ranges. Keywords: welding, metallography, ASTM A36 steel, mechanical properties. Resumen El presente trabajo tuvo como objetivo evaluar las propiedades mecánicas y realizar la caracterización metalográfica de las juntas soldadas a tope de acero ASTM A36, con material de aporte ER70S-6 bajo el proceso GMAW, se lo desarrolló desde un punto de vista cuantitativo apegado a un enfoque correlacional y experimental, mediante técnicas de recopilación de datos y el análisis de contenidos, se establecieron los parámetros iniciales a tener en cuenta en el proceso de soldado, siendo estos: voltaje, amperaje y velocidad de alimentación del alambre, desarrollado el proceso experimental, se procedió a evaluar las propiedades y se caracterizó metalograficamente las uniones soldadas. Se analizaron tres espesores de placas, las cuales fueron soldadas en varias combinaciones con diferentes valores de parámetros, obteniéndose cuatro combinaciones por cada espesor. En cada una de estas combinaciones se realizaron pruebas de: ultrasonido, tracción, doblez de cara y raíz; y, posteriormente, se realizó el análisis metalográfico, enfocado en tres zonas de análisis: zona de fusión, zona afectada por calor y zona del metal base, adicional a esto, se determinó el ancho de la zona afectada por calor, el tamaño de grano y la dureza. Con base a lo anterior se identificaron cinco combinaciones cuyos cordones presentaron buenas propiedades, siendo las combinaciones de 250 IPM las más destacadas, dado que, con diversos rangos de voltaje y amperaje, las uniones soldadas presentaron buena soldabilidad en los tres espesores considerados. Palabras Clave: Soldadura, Metalografía, Acero ASTM A36, Propiedades Mecánicas.
Natural fibers are appealing due to its inexpensive price, small weight, and high specific modulus, renewable nature, as well as biodegradability. Bamboo fibers is one of the most promising natural ...fibers (along with jute, sisal, bamboo, coir, banana, and others) owing to its low cost, light weight, quick growing cycle, and wide availability. The goal of this paper is to look into fibers orientation reinforced hybrid polymer nano composites that combine BAMBOO/E-GLASS and epoxy polymer in the ratios of E-glass fibre80 percent +bamboo 20 percent, E-glass Fibre70 percent +bamboo 30 percent, and E-glass Fibre60 percent +bamboo 40 percent of volume. The mechanical characteristics will be calculated by performing tests on the specimen's tension, hardness, and flexural qualities in line with ASTM standards. Finally, the values are verified when the testing results have been obtained.
•Integrated concept of biofuels production from brown macroalgae P. tetrastromatica.•The activation energy was determined as Ea=34.314kJmol−1.•Brown marine alga produced 7.8% of biodiesel by acid and ...alkali transesterification.•The fuel properties of Padina biodiesel meet the ASTM specifications.•Spent biomass of Padina yields 16.1% of bioethanol after fermentation process.
In this study, an integrated biomass conversion concept of producing liquid biofuels from brown marine macroalga Padina tetrastromatica was investigated. The algal biomass was collected from the Mandapam coastal region and processed under laboratory. Various parameters were studied to extract crude lipids from the biomass. A kinetic study was conducted for extracting the lipids from the biomass, which follows the first order kinetics and the lipid yield was 8.15wt.%. The activation energy; Ea=34.314kJmol−1 and their thermodynamic parameters were determined. Since the crude algal lipids contain high amount of free fatty acids, a sequential transesterification technique was examined and 7.8% of biodiesel (78mg/g algal biomass) yield was obtained. The biodiesel was analyzed by 1H and 13C–NMR spectroscopy and the conversion yield was estimated. Further, the biodiesel fuel properties were investigated and found that all the features fit the required ASTM D6751 specification limits. The residual biomass after lipid extraction was further explored for bioethanol production through the anaerobic fermentation process. The ethanol yield obtained after saccharification and fermentation were estimated and 161mg/g residue biomass was reported. The theoretical yield of conversion of hydrolysate to bioethanol was estimated and found to be 83.4%. Therefore, this study demonstrates that macroalga P. tetrastromatica biomass has great potential to produce liquid biofuels such as biodiesel and bioethanol.
Kevlar is commercial brand of fibers supporting para-aramids of light weight for major part of composite. It is applicable in robotics and automobile sectors where parts need to possess high tensile ...strength and excellent fatigue resistance. Carbon fibers are processed by thermal conversion of organic fiber with low Carbon content such as polyacrylonitrile (PAN) which contain around thousands of filaments. In the current work, samples are produced through Mark Two 3D printer and subjected under investigation for improving mechanical performance in evaluating tensile, flexural and impact behavior as per ASTM Standards. The differentiation is presented by finding the error between experiment and simulation results.
Investment cast ASTM F75 Cobalt Chromium Molybdenum (CoCrMo) alloy is commonly used for orthopaedic implants due to its biocompatibility and wear characteristics. Apart from the values listed in the ...standard, the relationship between individual processing parameters and the resulting physio-mechanical properties are not well documented. This study characterises the effect of melt temperature on the physical properties and chemical composition of investment cast CoCrMo alloy. Furnace loads of ∼23−34 kg of alloy were inductively melted using 125 kW of power and cast into tensile test bars and chemistry coupons. The bars were ground to create samples conforming to ASTM E8M and tested per ISO 6892-1. The oxygen and nitrogen content of the chemistry coupons were assessed using Inert Gas Fusion (IGF) per ASTM E1019. It was found that increasing the melt temperature had the effect of removing nitrogen from the melt and adding oxygen. It was also determined that there was a strong positive correlation between nitrogen content and strength values. If desired, there is scope to minimise both oxygen pickup and nitrogen loss, nitrogen is correlated to increased mechanical properties, of this alloy system by targeting lower melt temperatures. However, this would be at the expense of melt viscosity and mould filling.
The worldwide utilization of fossil energy, including its specific application as transportation fuel, significantly contributes to the continuous increase of the atmospheric CO2 concentration. ...Several solutions have been promoted or scheduled to reduce CO2 emissions. Among these solutions, the development of renewable energy resources, such as bio-fuels, offers important advantages as promoted by several countries and institutions who disclosed their plans to partly or totally use alternative renewable energy sources in the future. For the rapidly growing aviation sector, aviation fuel derived from fossil resources is still the major available energy source. The development of renewable aviation fuel is considered to be a promising future strategy to reduce related CO2 emissions. The worldwide total aviation fuel consumption by commercial airlines increased from about 260 million m³/year in 2005 to over 340 million m³/year in 2018, and a further annual increase of about 5% is expected till 2050.
Worldwide actions have hence been undertaken with respect to bio-aviation fuel production, distribution, and demonstration flying. As a relatively new topic, there are a lot of remaining challenges in technology development, fuel certification and distribution. The production technology, policy and environmental impact of bio-aviation fuel were comprehensively reviewed, including its production by the catalytic conversion of lipids, by the conversion of carbohydrates or lignocellulosic biomass, and by developing bio-refinery concepts for bio-aviation fuel production. The future reduction of CO2 emissions in the aviation sector requires an improvement of the biomass to aviation fuel production technology through the correct integration of biology, chemical engineering, and energy crops. The paper illustrates this potential integration through reviewing the current research in the production of aviation fuels from biomass, including the complete industrial chain from airplane manufacturer, aviation fuel producer and provider, airline strategies, and ongoing R&D, bearing in mind that major efforts are required to foster the development of the cost-effective production of renewable aviation fuel. The different topics of the Table of contents will be subsequently dealt with.
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•Tensile and fatigue properties of CM and PBF-LB samples are compared.•Integrated characterization approaches are employed to reveal fatigue mechanisms.•The importance of cellular ...structures on fatigue properties is highlighted.•The difference in fatigue properties between PBF-LB and CM samples is explained.
The mechanical properties of ASTM F1684 (Invar 36) alloy manufactured via laser beam powder-bed-fusion (PBF-LB) technique are strongly influenced by the non-equilibrium solidification microstructure. Due to the complexity of printed microstructure, e.g., the presence of melted pools, nano-precipitates, and high-density dislocations, it is very challenging to disentangle the specific mechanisms responsible for the fatigue properties. Here, a comparative investigation of the fatigue properties between PBF-LB and conventionally manufactured (CM) samples was conducted. Dedicated characterizations, including electron channeling contrast imaging (ECCI), and high-angular resolution EBSD (HR-EBSD), were performed. The mid-cycle (104–105 cycles) fatigue behaviors of both samples are comparable, while the fatigue resistance of PBF-LB sample becomes inferior at high-cycle range (≥106 cycles). This disparity can be ascribed to the competing effect between crack nucleation and propagation. PBF-LB samples are more susceptible to fatigue crack initiation due to the printed macro-defects. Whereas, the homogeneous plastic deformation and the grain fragmentation, both triggered by the ultrafine cellular structure, efficiently mitigate crack propagation rates. Based on these findings, the current understanding of the underlying mechanisms governing the fatigue performance of PBF-LB Invar 36 alloy is deepened, emphasizing the significant advantages of non-equilibrium solidification microstructure in retarding fatigue crack propagation.
Crack growth in a naturally corroded bridge steel Ali, K; Peng, D; Jones, R ...
Fatigue & fracture of engineering materials & structures,
July 2017, 2017-07-00, Letnik:
40, Številka:
7
Journal Article
Recenzirano
Odprti dostop
This paper summarises the findings of an international collaborative programme that focuses on the problem of the growth of cracks that arise from natural corrosion in bridge steels. The experimental ...data presented in this paper confirm that the bridge steel da/dN versus ΔK relationship is similar to that seen by the high‐strength aerospace steels D6ac and 4340. It is then shown that the methodology developed to predict the growth of small naturally occurring cracks in aerospace materials can also be used to compute the growth of cracks that arise because of natural corrosion in bridge steels.
•Successful isolation of nanocellulose fibres from arecanut husk by a chemo-mechanical method.•The nanocellulose fibrils were of 3–5nm diameter and high thermal stability.•Nanocellulose fibrils were ...highly crystalline in nature.•The aspect ratio of nanofibrils is found to be 120–150.•The method opens up a means for effective utilization of waste product-arecanut husk.
The isolation of cellulose nanofibres from arecanut husk was achieved by a chemo-mechanical method thereby opening up a means for utilizing a waste product more effectively. The chemical processes involved alkali treatment, acid hydrolysis, and bleaching. The mechanical fibrillation was performed via grinding and homogenization. The chemical constituents at different stages of treatment of fibres were analyzed according to the ASTM standards. Morphological characterization was done using the scanning electron microscopy (SEM), field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The isolated nanofibers had an average diameter of below 10 nanometres and a very high aspect ratio in the range 120–150. Fourier transform infrared spectroscopy (FT-IR) showed the effective removal of the non cellulosic components. The crystallinity was increased with successive treatments as shown by the X-ray diffraction analysis (XRD). The TGA studies revealed a good thermal stability for the isolated nanofibres.
The potential use of aluminium oxide nanoparticles as nanofuel additives was investigated on honge oil methyl ester and diesel fuel blend. The nanofuel blends were prepared by dispersing aluminium ...oxide in varying quantities in a HOME(B20) (20% biodiesel+80% diesel). Sodium dodecyl sulfate (SDS), an anionic surfactant, was used for a stable dispersion of aluminium oxide nanoparticles in the fuel blends. HOME(B20) fuel with concentration levels of 20, 40, and 60 ppm of aluminium oxide nanoparticles (HOME20, HOME2040 and HOME2060) with varying ratios of SDS surfactants were prepared using ultrasonication technique. The investigated properties of diesel, honge oil biodiesel and nanofuel blends were in agreement with the ASTM D6751-15 standards. The dispersion and homogeneity were established and characterized by using the Ultraviolet–Visible (UV–Vis) spectrometry. The UV–Vis spectrometry results illustrated an increase in absorbance level with a relative increase in the concentration of surfactant. The highest absolute value of UV-absorbency was observed for a mass fraction of 1:4 (Al2O3 NPs to SDS ratio). The investigation was performed at a constant speed of 1500 rpm, and BP of 0 kW, 1.04 kW, 3.12 kW, 4.16 kW and 5.20 kW. The fuel HOME2040 demonstrated an overall improvement in the engine parameters, the brake thermal efficiency (BTE) enhanced by 10.57%, while there was a decline in brake specific fuel consumption (BSFC) by 11.65% and the engine exhaust emission: HC, CO, and smoke reduced by 26.72%, 48.43%, and 22.84%, while the NOx increased by 11.27%. Similarly, the addition of aluminium oxide nanoparticles in HOME(B20) fuel blend resulted in decent reduction in the combustion duration (CD), ignition delay period (ID), improvement in the peak pressure, and a marginal increase in heat release rate (HRR) and cylinder pressure at maximum loading conditions. Based on the experimental results, it is concluded that the aluminium oxide nanoparticles in HOME(B20) fuel demonstrated an overall improvement in the engine characteristics.
•Al2O3 NPs-SDS surfactant ratio of 1:4, demonstrated highest UV–Vis absorbance.•Honge yielded 85% HOME, nanofuel properties were comparable with ASTM standards.•HOME2040 nanofuel enhanced BTE by 10.57% and reduced BSFC by 11.65%.•HOME2040 reduced emissions of CO, HC and smoke by 47.43%, 37.72% and 27.84%.•The HRR, PP improved and CD, ID reduced, while NOX increased for nanofuel blends.
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