Papers by Keyword: Aluminum Alloy

Abstract: Cleaner melt transfer is critical to the broader use of recycled aluminium alloys in high-end structural casting applications, where oxide bifilms and intermetallic inclusions, such as Fe-containing intermetallics, can significantly affect the casting's mechanical properties. In counter-gravity low- and high-pressure casting, the launder system must not only promote the sedimentation of inclusions but also deliver a stable, cleaner melt to the crucible. Prior research showed that 15° double baffles in the mid-section of the sedimentation launder at a flow rate of 100 kg·h^-1 provide high efficiency. The present work investigates the influence of baffle design at the launder-crucible interface, where the melt enters the crucible before casting. Fluid dynamic simulations were carried out at a 100 kg·h^-1 flow rate for three inlet configurations: (i) full baffle; (ii) lifted baffle; and (iii) split baffle. Inclusions of various densities and diameters were tracked. Results indicate that the full baffle, while beneficial as a benchmark and efficient, is impractical because it generates fresh oxide surfaces. The lifted baffle provided the most effective reduction in inclusions, like the full baffle setup, enhancing sedimentation and suppressing entrainment, while the split baffle showed intermediate behaviour. Moreover, the lifted configuration promoted centrifugal flow (at lower velocities, it still made a partial contribution) within the crucible, directing inclusions towards the crucible wall and the stagnation-velocity zone, and enabling the crucible itself to act as a final sedimentation stage before the counter-gravity pump extracts the melt. These results demonstrate that combining mid-launder optimisation with crucible inlet baffle design enables cleaner, more automated melt delivery, thereby strengthening the use of recycled aluminium alloys in structural casting applications.

Abstract: Predicting the deformation behavior of rolled and extruded light metal alloys is a challenging task. Due to the high cost of experimental analysis, finite element simulations are often required. A variety of material models at different scales are available for practical use. In this work, the viscoplastic self-consistent (VPSC) approach is employed to consider microstructural effects. These can be incorporated by using measured crystal sizes and orientations - called texture - of the alloy under consideration. For each integration point in the FE mesh, a corresponding texture is assigned and individually deformed in LS-Dyna^®, where VPSC is implemented as a user-defined material model - referred to as FE-VPSC. This study focuses on preprocessing of texture data as well as their compression for accurate and faster FE simulations. For verifying the simulations, a comparison with digital image correlation (DIC) of experimental puncture tests was conducted.

Abstract: With the increasing demand for lightweight materials, the combination of aluminum and magnesium sheets enables the development of advanced laminates with a balanced combination of strength and ductility, making them suitable for forming applications. This work investigates the effect of rolling temperature on the mechanical behavior and formability of AA1050/AZ31/AA1050 sheets produced by roll bonding in the temperature range of 250–450°C. Tensile tests showed that the yield stress is weakly affected by rolling temperature, whereas the ultimate tensile strength increases up to 350°C and then stabilizes. The elongation at fracture increases monotonically with temperature, indicating improved ductility at higher rolling temperatures. Microhardness measurements revealed softening of the aluminum sheets with increasing temperature, while limited variations were observed in the AZ31 sheet. Formability was evaluated by Erichsen Cupping test. The maximum load and extension at break remained nearly constant over the investigated temperature range; however, higher rolling temperatures led to reduced delamination and improved interfacial bonding integrity during deformation. The results indicate that roll bonding at elevated temperatures promotes better strain distribution and enhanced bonding quality. Overall, roll bonding at 450°C provides the most favorable combination of mechanical performance, formability, and interfacial stability, making the produced sheets suitable for lightweight forming applications.

Abstract: Additive manufacturing by laser powder bed fusion (LPBF) is increasingly applied to aluminium alloys; however, the resulting surface quality and machining behaviour remain critical challenges, particularly when post-processing is required. In this context, the interaction between LPBF process parameters and advanced cooling strategies during machining remains largely unexplored.This study examines the impact of cryogenic machining on the surface integrity of LPBF-produced AlSi7Mg components, fabricated with varying layer thicknesses. Specimens were machined under fixed cutting parameters using either conventional flood cooling or cryogenic cooling. Cutting forces, surface roughness, defect morphology, and subsurface microstructure were systematically evaluated.Cryogenic cooling consistently reduced cutting forces and improved surface quality, effectively suppressing tearing formation. In contrast, under flood cooling, the influence of the microstructural differences induced by layer thickness remained significant, with increasing LPBF layer thickness further enhancing both surface and subsurface integrity. Overall, the results reveal a strong interaction between LPBF parameters and cooling strategy, highlighting the unexpectedly beneficial role of cryogenic machining in improving the surface integrity of LPBF-processed AlSi7Mg alloys.

Abstract: The present study aims to investigate the anisotropic creep behaviour of aluminium alloy 2139 during artificial ageing, through in situ thermomechanical loadings under Electron Backscattered Diffraction (EBSD). EBSD analysis enabled the characterisation of microstructural parameters and the identification of grain misorientations which were further correlated with macroscopic creep strain. In situ analyses were conducted within a Scanning Electron Microscope (SEM) using a micro‑tensile stage that allows simultaneous heating and mechanical loading. Creep tests were performed at 160°C under 50, 100 and 150 MPa along three different orientations in order to investigate the creep behaviour of the alloy. Kernel Average Misorientation (KAM) maps showed a progressive increase of the average KAM values for the different loading conditions, reaching a saturation value after 10 hours. Ex situ tensile tests were conducted on creep‑aged specimens using Digital Image Correlation (DIC). The main mechanical property evolutions (averaged across all orientations) are a 45 % increase in yield stress, a 10 % increase in ultimate tensile stress and a reduction in ductility, characterised by a notable decrease in elongation. Further works will focus on the result repeatability, as well as on the influence of prior deformation on the creep strain.

Abstract: In the transition to a circular economy in the automotive sector, it is essential to integrate recycled (or secondary) aluminum alloys into extrusion processes, while ensuring that their performance is as close as possible to that of primary alloys. Within the Horizon Europe ZEvRA project, this study aims to analyze and investigate the hot deformation behavior of four aluminum alloys, two primary alloys (AA6082 Primary and AA7108) and two recycled alloys (AA6082 Recycled and AA6061), in order to demonstrate their potential suitability for automotive applications. Hot torsion tests were conducted under temperature and strain rate conditions representative of industrial extrusion processes. Four different temperatures (400, 450, 500, and 550 °C) and four different strain rates (0.01, 0.1, 1, and 10 s⁻¹) were investigated, allowing the achievement of significantly higher strain levels compared to conventional standard tensile and compression tests. Subsequently, the flow stress curves obtained from the torsion tests were analyzed to evaluate the influence of temperature and strain rate on the plastic deformation behavior of the material and on the associated dynamic softening mechanisms. The results demonstrate a comparable deformation behavior between primary and secondary alloys, confirming the feasibility and full compatibility of recycled alloys for high-performance industrial extrusion applications. Furthermore, the experimental results provide a solid basis for the development of robust constitutive models to support FEM simulations aimed at optimizing metal forming pocesses within a circular manufacturing framework.

Abstract: This paper presents a comprehensive structural, modal, and random vibration analysis of the SEAMS Payload using ANSYS 18.1 simulation tools. As a preliminary design-phase study, its goal is to perform a trade-off analysis between common aerospace materials before physical prototyping and validation. The study evaluates three aluminum alloys—5052- H32, 6061-T6, and 7075-T6—to optimize the payload frame structure for mechanical stresses encountered during launch and space operations. The analysis includes static structural loading to assess deformation and stress distribution, vibrational modal analysis to determine natural frequencies and mode shapes, and random vibration analysis to simulate launch-induced dynamic excitation. The simulation outcomes highlight the critical role of material selection in enhancing structural integrity, maximizing safety margins, and ensuring mechanical reliability of the payload in harsh launch environments.

Abstract: Fatigue damage is one of the key degradation mechanisms affecting the service life and reliability of aluminum alloys in a wide range of technical applications. The present study focuses on the fracture mechanisms of aluminum alloys under cyclic loading, with a view to the initiation and analysis of fatigue crack propagation in the context of the microstructural characteristics of the material. Special attention was paid to the influence of grain morphology, distribution and type of intermetallic phases, as well as the presence of casting defects on the initiation and development of cracks. Fatigue experiments were performed on a selected Al-Mg alloy of the EN AC 51200 type for the use of three-point bending loading. The results show that the key factors affecting the fatigue behavior are the size and distribution of precipitates, the nature of the interfaces between the phases and the occurrence of microcracks initiated mainly in areas of stress concentration. The knowledge gained contributes to a deeper understanding of fatigue mechanisms in aluminum alloys and provides a basis for their optimization in terms of composition and technological processing in order to increase their resistance to fatigue failures.

Abstract: To investigate the effect of the oxygen amount involved in mechanical alloying (MA) of Al and Y₂O₃ powders on the phase evolution of the alloy powders, two types of MA were performed: MA with low and high oxygen content in the MA atmosphere. Analyses of the lattice parameter and composition of the Al matrix by X-ray diffraction and scanning electron microscopy with energy dispersive X-ray spectroscopy, respectively, and the integrated intensity of Y₂O₃ indicated that in the low-oxygen MA, the driving force for Y₂O₃ precipitation was small and Y and O dissolved into the matrix, producing supersaturated solid solution powder, while in the high-oxygen MA, the driving force for Y₂O₃ precipitation was large, resulting in the formation of Y₂O₃-precipitated powder.

Abstract: The shear band observed during tensile tests of AA5083 aluminum alloys with different grain sizes were visualized using a two-dimensional electronic speckle pattern interferometer. The effect of grain boundaries on shear band formation was investigated by extracting displacement and strain fields from interference fringe patterns and stress-strain curves. The intensity of stress oscillations and the strain level at which shear bands appeared were dependent on grain size. Small-grained specimens exhibited regular shear band formation with clear serrations, while large-grained specimens showed delayed and irregular bands with reduced stress oscillations. The formation and propagation of shear bands across grain boundaries were further analyzed from the perspective of wave dynamics.