Materials Science Forum Vol. 1164

Abstract: Aluminium alloys are widely used in the automotive and aerospace industries, where permanent fastening methods are commonly employed to join aluminium sheets and components. Many aluminium alloys are known for their high strength-to-weight ratio, while others are favoured for their availability and cost-effectiveness. In modern applications, dissimilar aluminium alloys are often joined to achieve enhanced performance. This study explored the effects of artificial aging on the microstructural and mechanical properties of weld joints at varying temperatures. Significant microstructural differences were observed between the heat-affected zone (HAZ) and the weld zone (WZ). Coarse grains in the HAZ enhanced ductility, while the fine-grained structure and increased precipitate formation in the WZ improved strength but reduced ductility. Aging at 165°C induced notable changes, with precipitate formation causing a 30% reduction in elongation and a 3.6% increase in ultimate tensile strength (UTS), attributed to precipitation hardening and improved bonding. At 175°C, mechanical properties further improved, with a 16% increase in yield strength (YS) and up to a 7.7% rise in UTS. The higher temperature facilitated greater precipitate formation, as confirmed by microstructural analysis, enhancing joint strength. However, this improvement came at the cost of ductility, with a 39.3% reduction in elongation due to restricted dislocation movement caused by the precipitates. Thermal conductivity variations in the welded plates influenced heat distribution and precipitate formation during aging. The process also reduced residual stresses from welding, enhancing diffusion and metallic bonding. Overall, artificial aging improved strength and stiffness but significantly decreased ductility, with aging at 175°C yielding optimal mechanical performance despite the trade-off in ductility.

Abstract: Conventional welding of lightweight metals like aluminium and magnesium alloys raises concerns about joint strength and ductility. Conversely, friction stir welding (FSW) improves both by bonding materials through plastic deformation. This study revealed a clear correlation between tool feed rates and the mechanical performance of the joints. At lower feed rates, controlled plastic flow resulted in robust joint formation, enhancing both Ultimate tensile strength and Yield strength. Conversely, escalating the feed rate compromised joint strength due to imperfect joints and inadequate plastic flow. Artificial aging was found to play a pivotal role in enhancing the mechanical properties of FSW joints. Higher feed rates, despite initially leading to reduced ductility, showed improvements in yield strength following aging, primarily attributed to the reduction of flaws and defects within the joints. Artificial aging contributed to elevated yield strength values through grain boundary sizing and precipitate formation. However, it's important to note that the improvement in strength was not uniform across all feed rates, indicating that the influence of post-aging treatment was more pronounced for joints produced at feed rates other than 450 mm/min. Ductility experienced a significant decline (almost 50%) after artificial aging, especially for joints formed at higher feed rates, highlighting the trade-off between strength and ductility. Findings aid FSW optimization, designing joints with desired mechanical traits for applications valuing strength, ductility, and aging effects.

Abstract: Nanoindentation, an advanced technique employed for characterizing materials, facilitates the precise determination of their hardness and Young's modulus by applying a specific, controlled force through an indenter, enabling highly localized deformation and measurement at nanometer scales. The nanoindentation gives us the view of the isotropic and anisotropic features of the materials by analyzing the zone beneath the indenter. The application of Bulk Metallic Glass (BMG) alloy, renowned for its unique combination of high strength, exceptional elasticity, and superior corrosion resistance, spans diverse industries including aerospace, biomedical, and consumer electronics. The study focuses on conducting nanoindentation analysis on the BMG alloy, aiming to characterize its deformation behavior. This involved utilizing Scanning Electron Microscopy (SEM) to discern deformation characteristics, followed by validation of the findings through simulations, ensuring robustness and reliability of the results. The modulus, determined to be 227GPa, provided insight into the material's structural rigidity, and the hardness 14.8GPa offered an indication of its resistance to localized plastic deformation. The results have been compared with the simulation results where the modulus was 242GPa and the hardness was 16.1GPa.

Abstract: Titanium is widely used in aerospace and medical industries for its high strength-to-weight ratio and corrosion resistance, while Inconel 718 is favored in aerospace and power generation for its exceptional mechanical strength and oxidation resistance at high temperatures. It’s challenging to directly combine the Inconel 718 and the titanium, so the interlayer of vanadium is used which causes the strengthening of the bond by the formation of inter-metallics (TiaNib, NixVy). In this study, the RVE model was developed in order to examine the mechanical properties (i.e. Modulus, Poisson ratio) of the inter-metallics, by examining their microstructures. Furthermore, nanoindentation techniques are employed across different zones of the weldment to determine the modulus and hardness values. At the vanadium-Inconel interface, hardness and modulus values were observed to range from 2 to 8.5GPa and 130 to 205GPa respectively. The maximum error in hardness between the experimental and simulation was 3.75%. The pile up behavior was also examined in the simulation setup to determine the amount of plastic zone in the indent.

Abstract: The primary objectives include investigating the mechanical properties of used construction steel, and evaluating the feasibility of reusing the old materials in green construction projects. The methodology involves gathering samples from demolition sites which are over 40 to 50 years old(1980-1985 construction sites), conducting mechanical testing (such as tensile test and bending test), and performing microstructural analysis.By promoting the utilization of used construction steel, the project seeks to reduce waste, lower material costs, and minimize the environmental impact for sustainable activities. The results we found were that the average maximum load the material can bear was 1.35KN and was bended till 6mm. The average grain size of the material was found to be 20µm. the average elongation percentage came out to be 15.27% and the elements of the material identifies that it is of grade A-36 Steel.Ultimately, this project aspires to facilitate a shift towards more eco-friendly construction practices and supporting the construction industry's transition to sustainable development.

Abstract: In this study, researchers investigated the effectiveness of silver nanoparticles (AgNPs) combined with powder extracts from Moringa oleifera (Malunggay) for inhibiting corrosion on A36 mild steel, a common material used in the oil and gas industry. The synthesis process involved mixing AgNPs with Moringa oleifera extracts at different concentrations in acidic conditions and varying temperatures. Characterization techniques such as UV-Vis Spectroscopy, FT-IR, and TEM were used to analyze the structural and functional properties of the resulting Moringa-AgNPs. The study aimed to evaluate how these nanoparticles affected the corrosion resistance of A36 steel under different conditions, including temperature and inhibitor concentration, by assessing parameters like weight loss and corrosion rate. SEM/EDS analysis provided further insights. Overall, the research suggests that incorporating Moringa-AgNPs could be a promising strategy to reduce corrosion rates in the oil and gas industry.

Abstract: Epoxy resins are widely recognised as the most commonly used polymers, playing a crucial role in both industrial and domestic applications; however, the effect of secondary amine volume on the electrophoretic deposition (EPD) performance of epoxy resin remains underexplored. This study investigates the influence of varying volumes of N-methylethanolamine (MEA) during the synthesis of cationic epoxy on the chemical composition, thickness, surface morphology, and dielectric properties of electrodeposited epoxy coatings at a voltage of 60 V. Cationic diglycidyl ether of bisphenol A (DGEBA) epoxy resin was formulated with 0.5, 1.0, and 1.5 ml MEA, and then deposited onto galvanised substrates via EPD. Increasing the MEA volume from 0.5 ml to 1.5 ml during the formulation of cationic DGEBA resulted in a 50.6% reduction in deposited coating thickness (from 46.6 µm to 23.0 µm) and a 98% decrease in the corresponding dielectric constant (from 102 to 1.98 at a frequency of 1.27 Hz). These variations were confirmed by Fourier-transform infrared spectroscopy, electrochemical impedance spectroscopy, and field-emission scanning electron microscopy, which indicated changes in chemical bonding and surface uniformity. The findings highlight the critical role of MEA volume in determining the performance of electrodeposited epoxy coatings and offer guidance for optimising EPD formulations for improved insulation and structural stability.

Abstract: The structural-phase compositions of the alloy obtained through reduction melting with oxide waste use from the production of high-alloy steels and alloys with different charge compositions have been studied. It is crucial to determine the technological parameters that ensure the reduction of alloying element losses during the production and use of the alloying material. In the phase composition of the resulting alloy, a solid solution of alloying elements and carbon in the lattice of γ -Fe, Fe3C, as well as FeNi in the case of adding alloyed metal chips to the charge has been found.At the same time, a relative increase in the content of alloying elements in the studied areas of the alloy has been ensured (wt.%): Cr – from 1.84–32.90 to 0.59–43.98; Ni – from 1.41–20.74 to 4.24–45.02; Mo – from 0.35–1.30 to 0.00–11.89; W – from 0.00–0.08 to 0.00–21.37, respectively. This led to the formation of new phase structures containing refractory elements, presumably of carbide and intermetallic nature, which been observed in microstructural images. The proportion of residual carbon in the form of carbide component and residual unreacted reductant is aimed at providing the required reducing capacity during the alloy usage. The studies have identified new technological aspects of processing high-alloy industrial waste, resulting in a resource-efficient alloying material with the potential to partially replace standard ferroalloys in steel production.

Abstract: The work investigates the effect of additives to the primary material of a current-carrying conductor on the heating temperature of an electrical wire, exemplified by a single-core aluminium wire with single-layer polyvinyl chloride insulation. It establishes the dependencies between the wire's heating temperature and its operating time under load currents that are lower, close to, and higher than the permissible levels set by regulations. The effect of chromium, vanadium, and titanium additives to the primary material of a current-carrying conductor on the wire's heating temperature during operation is also evaluated. Even small amounts of additives (less than 0.1%) to the primary material of a current-carrying conductor can affect the heating temperature of the loaded wire. Chromium additives have the most effect, while titanium additives have the least effect. The study demonstrates that during operation, a loaded electrical wire heats the least if the primary material of its current-carrying conductor has none of the additives considered in the article.