Search Results (163)

This study established a marine atmospheric corrosion prediction model by comparing the corrosion behavior of 7075 aluminum alloy in neutral salt spray tests and outdoor exposure tests conducted in the coastal atmosphere of Hainan. The results show that severe rusting occurred after 96 h of neutral salt spray testing, with loose white cluster-like corrosion products mainly composed of Al(OH)₃ and Al₂O₃. The thickening of the corrosion product layer slowed down the corrosion process, following a nonlinear power-law kinetic relationship. In the later stage, potential dropped sharply due to product layer spallation, and recovered as new corrosion products formed, confirming that the stability of the product layer is critical for protection. Under coastal atmospheric exposure, the composition of corrosion products was similar to that observed in the salt spray test, but the actual corrosion rate was affected by environmental dynamic equilibrium. The acceleration factor of the neutral salt spray test corresponding to the same corrosion amount in the Hainan marine atmosphere exhibited a declining trend, reflecting that differences in the protective nature of the corrosion product layer were influenced by environmental factors. Electrochemical analysis indicated that both tests showed similar current–potential synergistic variation mechanisms dominated by product layer stability. In summary, while the neutral salt spray test effectively simulates the chloride-induced corrosion mechanism in marine atmospheres, its kinetic model cannot directly predict real corrosion behavior through a simple acceleration factor, as environmental complexity must be considered. Full article

The roll bonding of 7075/1060 composite laminates offers a promising approach toward the increase in toughness of aluminum layered composites. In this paper, 7075 and 1060 aluminum alloy plates were hot roll bonded to fabricate multilayered composite laminates. Solid solution at 470 °C for different holding times and subsequent aging were carried out for all the laminates. This study investigated the effect of holding times on the interfacial microstructure and interfacial bonding strength of the laminates. The interfacial shear strength was found to increase with longer holding times, which was attributed to the solid solution strengthening of the 1060 layer resulting from element diffusion. The findings also reveal that both tensile strength and toughness are positively correlated with the holding time of the solid solution, and there is a simultaneous improvement of tensile strength and toughness as the holding time increases. Microstructural characterization of the crack path profile of the Charpy impact and bending test indicates that interfacial delamination and main crack deflection become pronounced with the increase in holding time, and these lead to an increase in the fracture resistance in the crack-arrester orientation. Full article

This work quantifies the environmental sensitivity of tartaric–sulfuric acid (TSA) anodized and sealed 6061 and 7075 aluminum. Five alloy–temper states (6061-T4, 6061-T62, 7075-T0, 7075-T62, and 7075-T73) were TSA-treated, pore sealed and then exposed for eight weeks (56 days) to ambient air, 11 wt.% NaCl brine, or a microbiological medium, with weekly +20 °C/−20 °C freeze–thaw cycles. Tensile tests assessing yield strength, ultimate strength, and elongation were conducted. Strength losses were modest in ambient conditions (<5%) but increased to ≈5–10% for yield and ≈2–9% for ultimate under saline and microbial conditions, particularly in the annealed 7075-T0 and peak-aged 7075-T62 states. Ductility was more sensitive, declining up to ≈30% for 6061-T4 and 6061-T62 in harsh media. Permutation-based inference within an additive screening model indicated that environmental exposure is strongly associated with the dominant share of the observed variability (R²_env ≈ 0.91–0.93 for yield, ultimate strength, and elongation), within the limits of the present dataset. These results suggest that freeze–thaw cycling, chloride exposure, and microbiological activity are consistent with the observed degradation trends. Over-aged 7075-T73 retained properties better than T62, highlighting the roles of temper and pore sealing quality in cold, saline, and microbiologically active service. Full article

This study investigates the effects of welding current on the microstructure, mechanical properties, and corrosion behavior of 7075/7075 pulsed metal inert gas (P-MIG) welded joints. Welding experiments were conducted at currents of 190 A, 200 A, and 210 A using ER5356 filler wire, with the joints analyzed through optical microscopy (OM), scanning electron microscopy (SEM/EDS), and tensile and hardness testing, as well as intergranular and electrochemical corrosion evaluations. The results reveal that increasing welding current alters the solidification dynamics and precipitation behavior in the WZ. At 190 A, refined and uniformly distributed dendrites were obtained, whereas at 210 A, grains coarsened and elemental segregation was more pronounced. The weld hardness exhibited a trend of first increasing and then slightly decreasing with increasing welding current, with a maximum value of 99.5 HV0.1 obtained at 200 A. Similarly, the tensile strength improved with increasing welding current, reaching 257.7 MPa with 8% elongation at 210 A. Corrosion resistance exhibited a non-monotonic trend, with the best performance observed at 200 A, as indicated by the shallowest intergranular corrosion depth, the most positive open-circuit potential, and the highest charge transfer resistance in electrochemical impedance spectroscopy. The findings demonstrate that welding current is a critical parameter controlling the balance between microstructural refinement, mechanical strengthening, and corrosion resistance, and that 200 A represents the optimal condition under the investigated parameters. These insights provide theoretical guidance and experimental evidence for process optimization in the welding of high-strength aluminum alloys. Full article

Large Strain Extrusion Machining (LSEM) is an intensive plastic deformation process evolved from conventional machining, enabling effective control over chip morphology and grain refinement. This process often generates high cutting temperatures and frictional instability during machining, which degrades material properties and accelerates tool wear. This study proposes a technique combining microtextured tools with LSEM to optimize cutting performance. By designing different microtextured tools (parallel-to-cutting-edge microtextured tools (P-T) and perpendicular-to-cutting-edge microtextured tools (V-T)), cutting experiments were conducted on 7075 aluminum alloy to systematically investigate the effects of microtextured LSEM on cutting performance and chip formation. Results indicate that microtextured tools effectively reduce cutting temperatures. Compared to non-textured tools (N-T), microtextured tools can lower maximum cutting temperatures by up to 13.20% (36.56 °C). Microtextured LSEM suppresses serration formation, leading to more stable chip formation. The serration degree of chips produced by microtextured tools was reduced by up to 25.66% compared to N-T tools. XRD analysis indicates that microtextured tools significantly increase chip dislocation density, reaching nearly 2.77 times that of N-T tools, enhancing material microhardness and refining grain size. This study confirms that combining microtextured tools with LSEM synergistically optimizes chip morphology and improves the microstructural properties of Al7075, providing technical support for machining high-strength aluminum alloys. Full article

Laser weapons, characterized by their rapid response capabilities, precision targeting, and operational stealth, have emerged as essential directed energy systems for neutralizing missile, satellite, and drone threats. This paper examines the widely utilized 7075 high-strength aluminum alloy in military applications, conducting a comprehensive analysis of the material’s ablation characteristics under continuous laser exposure. The study elucidates the phase change phenomena and elemental separation mechanisms that occur as a result of ablation. Findings indicate that the aluminum (Al) element primarily undergoes a process of melting, driven by gravitational flow and subsequent resolidification, resulting in the formation of a bright silver Al-rich solidified layer at the base of the ablation zone. Conversely, the zinc (Zn) element vaporizes at elevated temperatures, with its byproducts oxidizing and condensing in the atmosphere, leading to the formation of gray- white zinc oxide (ZnO) deposits above the ablation area. This research highlights the synergistic damage mechanisms of vaporization and melting, thereby providing a critical theoretical framework for understanding the damage mechanisms associated with laser ablation of aluminum alloys. Full article

Diffusion bonding (DB) of aluminum alloys faces significant technical challenges, requiring thorough surface preparation and precise control of process parameters. To enhance the joint quality of 7B04 aluminum alloy sheets, pure aluminum (Al) and 7075 aluminum alloy powders were used as interlayers. In the DB experiments, nano-sized Al powder and micro-sized 7075 powders with different particle sizes served as interlayer materials. Compared to DB without an interlayer, using powder interlayers substantially reduced the bonding temperature while improving overall joint performance, with deformation kept below 6%. The lap shear strength (LSS) of the bonded 7B04 joints was significantly higher when 45 μm and 75 μm 7075 powders were used, compared to the 5 μm 7075 powder. The joint with a 50 nm Al powder interlayer achieved a maximum LSS of up to 220 MPa and exhibited considerably higher microhardness. Additionally, the mixed Al/7075 powder interlayer effectively decreased voids at the joint interface, contributing to increased LSS. Full article

The application of laser powder bed fusion (LPBF) to 7xxx-series aluminum alloys is fundamentally limited by hot cracking and porosity. This study demonstrates that adding 5 wt.% AlCoCrFeNi_2.1 high-entropy alloy (HEA) particles to 7075 aluminum alloy (AA7075) powder can effectively mitigate these issues. Microstructural characterization revealed that the HEA particles remained largely intact and formed a strong metallurgical bond with the α-Al matrix. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) analysis confirmed that this bonding is facilitated via the in situ formation of new intermetallic phases at the particle/matrix interface. X-ray diffraction (XRD) identified these phases as primarily Al₅Co₂ and Fe₃Ni₂. A key consequence of this reinforced interface is a significant change in cracking behavior; optical microscopy (OM) showed that long, continuous cracks typical of AA7075 were replaced by shorter, deflected cracks in the composite. While porosity was not eliminated, the addition of HEA stabilized the process, yielding a consistent density improvement of 0.5–1.5% across the processing window. This microstructural modification resulted in a substantial ~64% increase in average microhardness, which increased from 96.41 ± 9.81 HV_0.5 to 158.46 ± 11.33 HV_0.5. These results indicate that HEA reinforcement is a promising route for engineering the microstructure and improving the LPBF processability of high-strength aluminum alloys. Full article

The high-strength aluminum alloy 7B04 used in aircraft structures poses challenges in welding. In this study, 7075 aluminum alloy powder is used as an interlayer to strengthen the vacuum diffusion bonding (DB) joint of 7B04 aluminum alloy. Surface treatments with plasma activation before DB can effectively increase the bonding rate and lap shear strength (LSS) of the joint. The effects of DB temperature, pressure, and holding time on the joint LSS were analyzed by developing a quadratic regression model based on the response surface method (RSM). The model’s determination coefficient reached 99.52%, with a relative error of about 5%, making it suitable for 7B04 aluminum alloy DB process parameters optimization and joint performance prediction. Two sets of process parameters (505 °C-5.7 h-4.5 MPa and 515 °C-7.5 h-4.4 MPa) were acquired using the satisfaction function optimization method. Experimental results confirmed that the error between measured and predicted LSS is approximately 5%, and a higher LSS of 174 MPa was achieved at 515 °C-7.5 h-4.4 MPa. Full article

In many areas such as the automotive, aircraft, and building industries, the high-strength aluminum alloy Al 7075 is frequently used due to its appropriate properties as a lightweight structural material. However, due to modest weldability, it is challenging to obtain high-quality welds with suitable mechanical properties, as cracks are generated while welding. Moreover, in order to avoid post-welding heat treatments and the use of complex welding equipment, in this paper the Al 7075 alloy is welded with MIG under longitudinal vibrations by using the Al 4043 alloy as filler material. As a consequence of strengthening the HAZ through precipitation, the mechanical and structural properties of the welded joints can be improved. These are investigated both under longitudinal forced vibrations at 50 Hz and without such vibrations. The results reveal improvements in terms of reducing the risk of hot cracking, obtaining a band structure free of porosity of the welds, improving the hardness of the welds under vibrations by 8.7% to 12.5%, and improving the tensile strength of the plates welded under vibrations by 12 to 15.5% in comparison to no vibrations. In relation to other welding procedures, the proposed procedure is more cost-effective and the weld quality is improved during the welding process. Full article

Corner radius end mills (CREMs) are widely used in machining due to their unique tool geometry, which improves surface quality. Variations in cutting force during machining significantly impact machining quality. Therefore, precisely predicting cutting forces is critical for controlling machining chatter and enhancing accuracy. Traditional element force models have complex formulas and high computational demands when considering tool runout. This paper proposes a hybrid prediction model for CREMs that integrates the separate-edge-forecast method and the BP neural network. The integration approach incorporates runout effects into cutting force coefficients and addresses nonlinear effects from runout. The accuracy of the cutting force prediction model was validated through side milling on 7075 aluminum alloy. The results indicate that the maximum error between the predicted and measured forces is 9.43%, demonstrating that this model ensures high prediction accuracy while reducing computation cost. Full article

This study systematically investigates the effects of aging treatment (AT) on the microstructure and properties of Cr/DLC coatings deposited via cathodic arc ion plating onto the surface of ECAP-7075 aluminum alloy. Utilizing a comprehensive approach combining performance tests (nanoindentation, nanoscratch testing, dynamic polarization analysis) with characterization tests (scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy), the synergistic effects of equal channel angular pressing (ECAP) and aging treatment(AT) were elucidated. The results demonstrate that the combined ECAP and AT significantly enhance the coating’s performance. Specifically, AT promotes the precipitation of η’ phase within the 7075 aluminum alloy substrate, increases the size of Cr₇C₃ crystallites in the Cr-based interlayer, improves the crystallinity of the Cr₇C₃ phase on the (060) or (242) crystal planes, and elevates the sp³-C/sp²-C ratio in the diamond-like carbon(DLC) top layer, leading to partial healing of defects and a denser overall coating structure. These microstructural transformations, induced by AT, result in substantial improvements in the mechanical properties (hardness reaching 5.2 GPa, bond strength achieving 15.1 N) and corrosion resistance (corrosion potential increasing to -0.698 V) of the Cr/DLC-coated ECAP-7075 aluminum alloy. This enhanced combination of properties makes these coatings particularly well-suited for high-performance aerospace components requiring both wear resistance and corrosion protection in demanding environments. Full article

In order to obtain the optimal heat treatment process of Er-containing 7075 aluminum alloy, the effects of pre-stretching and the interval time between pre-stretching and aging on the microstructure and mechanical properties of Er-containing 7075 aluminum alloy during solution treatment followed by pre-stretching and two-stage aging processes were investigated by mechanical property tests, metallographic tests, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results show that the mechanical properties of Er-containing 7075 aluminum alloy can be significantly improved by increasing the extrusion ratio. Pre-stretching provides nucleation sites for the precipitation of reinforcing phases, accelerates the aging strengthening process, and shortens the peak aging time. The crack source of fracture in Er-containing 7075 aluminum alloy is attributed to the segregated second phases containing Cu and Er in the alloy. The research results have significant engineering significance for the optimization of the heat treatment process of Er-containing 7075 aluminum alloy. Full article

Ceramic oxide coatings were fabricated on 7075 aluminum alloy via micro-arc oxidation (MAO) in a silicate-phosphate electrolyte under voltages of 250 V, 300 V, and 350 V for 600 s. The effect of the applied voltage on the surface morphology, microstructure, phase composition, microhardness, roughness, coating thickness, and corrosion resistance was systematically studied. The coating obtained at 300 V demonstrated a dense structure with relatively low surface roughness (2.3 μm) and a thickness of approximately 70 μm. This sample also exhibited the most balanced performance, combining relatively high microhardness (~422 HV) and the lowest corrosion current density (6.1 × 10⁻⁷ A/cm²) in a 3.5 wt.% NaCl solution. X-ray diffraction patterns revealed the presence of both γ- and α-Al₂O₃ phases in all coated samples, with a relative increase in α-phase intensity observed at an intermediate voltage. The results demonstrate that the applied voltage plays a critical role in determining the coating structure and performance, offering insights into the surface treatment of high-strength aluminum alloys for engineering applications. Full article

Based on end-quenching and step-quenching experiments combined with scanning electron microscopy (SEM) and transmission electron microscopy (TEM), the quench sensitivity of a novel high-strength aluminum alloy was investigated and compared with that of GB/T 7075 and 7175 alloys; quench factor analysis (QFA) was employed to predict the hardness values of the alloy and investigate the effect of quenching rate on its mechanical properties. The experimental results indicate that when the cooling rate decreases from 402.5 °C/s to 3.6 °C/s, the hardness reduction rate of the novel high-strength aluminum alloy is 15%. Furthermore, the nose temperature of the time–temperature–property (TTP) curve for this alloy is 325 °C, with a critical transformation time of 0.4 s. The quench-sensitive temperature range is 219 °C to 427 °C, which is lower than the quenching sensitivity of 7075 and 7175 alloys. The new alloy reduces its quenching sensitivity by optimizing the composition of alloying elements. Furthermore, the QFA demonstrates high predictive accuracy, with a maximum error of 5%. The smaller the quenching factor τ, the greater the hardness of the alloy after aging. Combined with the TTP curve, the alloy properties are optimized by modulating the quenching rate. This study provides a theoretical basis for selecting hot forming–quenching integrated process parameters in automotive high-strength aluminum alloys. Full article