Journal of Materials Engineering and Performance最新文献

This study investigates the enhancement of corrosion resistance in Zn-Al coatings by the application of novel ZIF-8 hydrophobic films, synthesized using a secondary growth method with varying molar ratios. The effectiveness of ZIF-8 films was assessed through electrochemical corrosion tests, scanning electron microscopy, atomic force microscopy, and electron probe microanalysis. Results indicate that ZIF-8 films prepared by the secondary growth method exhibit greater density and smoothness compared to those produced by traditional methods. The ZIF-8 hydrophobic films significantly improved the corrosion resistance of Zn-Al coating, with the ZIF-8 film at a molar ratio of 1:16 demonstrating the best corrosion protection performance. After 2 h of corrosion, ZIF-8 films with a molar ratio of 1:16 demonstrated the highest corrosion resistance, achieving a charge transfer resistance (R_ct) of 13218 Ω/cm², which is two orders of magnitude higher than that of uncoated Zn-Al coating. ZIF-8 films exhibited significant corrosion protection potential on Zn-Al coatings, providing important theoretical and experimental support for the development of high-performance corrosion-resistant coating. This has broad application prospects, particularly in corrosion protection for metal structures in bridges and transportation infrastructure, such as the main cables of offshore bridges and cross-sea bridges.

The demand for high-strength and low-defect aluminum alloy welded structures has led to significant challenges in fusion welding technology, which is largely influenced by filler materials. This paper introduced a Sc/Zr microalloyed AlMg6 (AlMg6ScZr) filler wire for the welding of 2024 aluminum alloys. An AlCu4Mg1 filler wire was adopted for comparative analysis. Results demonstrate that the addition of AlMg6ScZr filler resulted in a better homogeneity of grain structure and a significant grain refinement in the weld zone, with a remarkable reduction in grain size of 59.3%. In contrast to the AlCu4Mg1 filler, no phases were continuously distributed along the grain boundaries in the weld zone. Nanoscale spherical Al₃(Sc, Zr) phase formed on the surface of the α-Al matrix and together with the separately distributed bone-like α-Al + S-Al₂CuMg + β-Al₃Mg₂ eutectics. The addition of AlMg6ScZr filler considerably improved the uniformity of hardness distribution, with a slight reduction of hardness values in the weld zone. The UTS and elongation were 318.0 MPa and 15.0%, respectively, showing an increase of 7.4% in UTS and 200% in elongation compared to the welds with AlCu4Mg1 filler. The results provide a valuable basis for obtaining high-performance fusion welds of high-strength aluminum alloys.

Conventional arc welding of low-carbon steel (LCS) often results in challenges such as extensive edge preparation, porosity, inadequate sidewall fusion, and a broad heat-affected zone, compromising joint integrity. To address these issues, this study explores the potential of rotating arc gas metal arc welding (RA-GMAW) as an advanced welding technique to enhance weld quality. The study investigates the RA-GMAW process on 6 mm thick AISI 1020 steel plates, focusing on the influence of arc rotation speed (ARS), arc rotating diameter (ARD), and gas flow rate (GFR). A face-centered central composite design (FCCCD) based on response surface methodology (RSM) is used to optimize process parameters. Analysis of variance (ANOVA) results reveal ARS as the most influential factor, followed by ARD and GFR. EBSD analysis demonstrates that increased ARS leads to finer grains and higher proportions of high-angle grain boundaries (HAGBs), enhancing mechanical properties. The EBSD results indicated that the welded sample 10 (1500 rpm, 5 mm, 14 l/min) shows a fine grain structure with an AGS of 5.09 ± 0.11 µm and a HAGB fraction of 54.12%. The optimized welding parameters, consisting of an ARS of 1500 rpm, ARD of 5 mm, and GFR of 14 l/min, yielded superior mechanical properties, including a maximum tensile strength of approximately 491 MPa, an elongation of around 15.4%, and a fusion zone hardness of about 208 HV. The RA-GMAW joint demonstrated an increase in tensile strength of 5.59% compared to the base metal and 26.1% compared to the non-rotating GMAW joint, highlighting the effectiveness of the RA-GMAW process in producing high-quality welds.

Additive Friction Stir Deposition (AFSD) is an emerging solid-state additive manufacturing technology that can deposit metals without melting and solidification. This characteristic makes AFSD a potential alternative to traditional fusion-based additive manufacturing technologies. Although deposition rate is closely related to the additive efficiency of AFSD, its effects on microstructural and mechanical properties remain unclear. This study investigates the effects of deposition rate on microstructure and mechanical properties by conducting experiments at deposition rates of 0.2, 0.3, 0.4, 0.5, 0.6, and 1. AFSD multi-layer structures were fabricated at different deposition rates, and specimens for microstructure and mechanical property testing were extracted using wire-cut EDM. The relationship between deposition rate, microstructure, and mechanical properties was analyzed through electron backscatter diffraction (EBSD), tensile testing, and hardness testing. At deposition rates of 0.2, 0.4, and 0.6, the average grain sizes were 9.5, 11.8, and 13.8 μm, respectively, indicating a positive correlation between grain size and deposition rate. However, the ultimate tensile strength decreased with increasing deposition rate, reaching 215, 203, and 196 MPa at deposition rates of 0.2, 0.4, and 0.6, respectively. Combining test results for heat input, friction torque, and axial force, the study demonstrates that variations in deposition rate induce changes in thermal and force inputs during the AFSD process, subsequently driving the evolution of microstructure and mechanical properties. Specifically, increased deposition rate leads to higher plastic deformation heat input and greater axial force, ultimately resulting in grain growth and diminished mechanical performance. The results provide an important reference for optimizing AFSD and increasing additive manufacturing efficiency.

In this study, the microstructure and mechanical properties of 7136 aluminum alloy thick plates (with a final thickness of 80 mm) at different position in homogenized, hot-rolled, and aged conditions were studied. The results demonstrate that the volume fraction of the second phase in homogenized ingots and hot-rolled thick plate exhibits the highest value at position 1/4 H, followed by surface, and the lowest value at position 1/2 H. Hot-rolled thick plate was more prone to dynamic recrystallization near the surface, and the volume fraction of recrystallization gradually decreases along the surface toward the center, resulting in uneven texture and mechanical properties. The maximum difference in tensile strength among the alloy samples taken at the different thickness positions in the TD and RD directions was 14.2%. Via aging, the alloy uniformly precipitates a large number of nano-scale η′ precipitates in different thicknesses position, and the size and volume fraction of the η′ phase exhibit negligible variations. Consequently, the mechanical properties demonstrate minimal variation, with a maximum tensile strength of 618.9 MPa and differences across various orientations and thicknesses position remaining below 6%.

Metal fused filament fabrication (MFFF), a type of additive manufacturing technology, involves heating and extruding metal filament materials to build objects layer by layer. This paper investigates the influence of printing parameters, including fill flow rate, raster angle, and building direction, on the microstructural characteristics, tensile properties, and magnetic properties of Fe-3 wt.% Si prepared by MFFF. Results indicate that porosity initially decreases and then increases with increasing infill flowrate, reaching a minimum at 108%. Different raster angles exhibit anisotropy, and the print direction significantly impacts porosity and properties. Specimens printed at an infill flowrate of 108%, with a raster angle of 45°/− 45°, and in a horizontal direction exhibit the lowest porosity, the anisotropy is not obvious, with a tensile strength of 505 MPa and yield strength of 355 MPa, maximum permeability is 11.37 mH/m, the saturation magnetic induction intensity is 1637 mT, and the initial permeability is 0.8541 mH/m.

The lithium-ion battery cells in electric vehicles are created in part by welding many layers of electrode foils to a tab to create the cell lead. While this process has conventionally involved an ultrasonic welding process, there is a desire to replace this process with laser welding to address certain limitations and remove a process step. The literature surrounding laser welding of multilayer thin foils to tabs is limited. This research aims to address this gap by developing a process window for green laser welding of multilayer foil-to-tab copper welds. Multiple copper foil layers, from 30 layers to 90 layers, were joined to a copper tab using a green laser with varying power and speed. The welds were analyzed based on micrographs, x-ray, failure load, and fracture mode. Process windows were developed for the various stack-ups. It was observed that very low heat input results in a narrow weld width and hence interfacial fracture under lap-shear loading. With suitable power and speed parameters, a process window exists where the welds have a minimum interface width greater than 180 µm, leading to fracture at the foil-weld fusion boundary. It was observed that excessive weld energy results in a weld with high porosity. Foil cut-through associated with excessive surface variation occurred under high speed and high-power conditions. As the number of foil layers increased, the process window is reduced due to the increasing number of defects present.

This study investigates the effects of incorporating surface-metallized graphene nano-sheets (GNS), specifically silver-coated GNS, into S390 high-speed steel (HSS) produced via powder metallurgy. The research focuses on evaluating the influence of GNS addition and post-sintering heat treatment on density, microstructure, hardness, wear resistance, and oxidation resistance. The silver coating on GNS improves interfacial bonding with the steel matrix, enhancing load transfer and dispersion. Results revealed that although the addition of GNS slightly decreased the density of sintered samples due to their low mass and increased porosity, heat treatment mitigated this effect by promoting densification. An optimal improvement was observed with 1 wt.% GNS, which resulted in a significant increase in hardness up to 957.8 HV after heat treatment compared to 215 HV for the untreated matrix. Wear resistance improved progressively with increasing GNS content, with heat treatment further reducing wear rates by 80% for the base matrix and 20% for the 1 wt.% GNS sample. Oxidation resistance was also enhanced due to the barrier effect of graphene and the formation of protective oxide films during heat treatment. These synergistic effects make silver-coated GNS a promising reinforcement for improving the mechanical and chemical performance of S390 HSS in high-temperature and high-wear applications.