Search Results (12)

The aim of this study was to determine the influence of heat treatment parameters on the microstructure and mechanical properties of the AlMn1Cu (EN AW-3003) aluminium alloy with a one-sided cladding layer of AlSi7.5 alloy (EN AW-4343). The investigation was conducted within an annealing temperature range of 200 °C to 500 °C, analysing changes in hardness, mechanical strength, formability, and planar anisotropy. The results clearly indicate that within the temperature range of 300–340 °C, an intensive process of static recrystallisation occurs, leading to the restoration of a fine-grained and homogeneous microstructure. This is accompanied by a sharp reduction in hardness and yield strength, along with a significant increase in ductility and deep drawing capability. A notable reduction in the anisotropy of plastic properties was also observed, confirming effective homogenisation of the material’s microstructure. The findings unambiguously demonstrate that heat treatment within the range of 300–500 °C enables the formation of an isotropic microstructure with low hardness and high formability, rendering the material particularly suitable for shaping thin-walled components, including heat exchangers. Full article

One of the most effective methods of improving the properties of aluminium alloys is grain refining using Al-Ti-B master alloys. In contrast, zirconium is a key alloying element, used mainly in 2xxx and 7xxx series aluminium alloys, where it contributes to dispersion enhancement and reduces the rate of dynamic recrystallisation. However, even trace amounts of zirconium—just a few hundredths of ppm—significantly reduce the performance of Al-Ti-B grain refiners, a phenomenon known as ‘Zr poisoning’. This study investigates the impact of holding time and the level of Al-5Ti-1B addition on the microstructure and properties of an AlMgSi(Cu) alloy containing 0.15 wt.% Zr, cast as 7-inch DC billets. The structure and phase distribution were characterised using optical microscopy (OM), scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). Grain size and morphology were evaluated through macrostructure analysis (etched cross-sections and polarised light microscopy), while chemical and elemental distributions were analysed via SEM-EDS and STEM-EDS mapping. Additionally, Brinell hardness measurements were conducted across the billet diameter to assess the correlation between grain size and mechanical properties. The results show that reducing holding time and increasing the Al-5Ti-1B addition improves grain refinement efficiency despite the presence of Zr. The finest grain structure (150–170 μm) and most homogeneous hardness distribution were achieved when the grain refiner was continuously fed during casting at 80 ppm B. These findings are supported by the literature and contribute to a deeper understanding of the Zr poisoning effect and its mitigation through optimized casting practice. Full article

This study presents the results of research on the influence of different contents of copper in aluminium alloys based on the 6xxx series on mechanical and structural properties. The investigation started with the alloying, and casting four billet variants with different copper content—0.8% Cu; 2B—1% Cu; 3A—1.2% Cu; and 3B—1.4% Cu. The prepared materials were homogenised and extruded on a 500T horizontal press with two different process temperatures and ram speeds ranging from 1 mm/s to 9 mm/s. After heat treating to the T6 and T5 tempers, their mechanical properties were tested. On this basis, the two most promising alloys 2A and 3B were selected and subjected to further tests. After extrusion and heat treatment of the profiles (to F, T1, T2, T5, and T5510), their mechanical properties were determined to select the preferred process parameters. Finally, a structural test based on crystallographic orientation based on the EBSD technique and TEM observations allowed for the characterisation of grain size, dispersoids, and phase analysis. Bright-field (BF) analysis allowed us to compare the deformed areas for T1, T5, and T5510 temperatures. The results showed significant growth in the mechanical properties of all the subjected alloys, and the best properties were shown for a Cu content of 1.4% with a tensile strength of 460 MPa and an elongation of 16% (T5510 tempering). The structural test showed an average grain size of 18 µm to 23 µm and solid solution decomposition differences for different heat-treating parameters. Full article

Experimental and finite element studies of the rotary friction welding (RFW) process of tungsten heavy alloy (THA) with aluminium alloy 5XXX series are presented. A 2.5D torsion simulation model including the circumferential effects was developed in this study. The temperature distributions, effective stress, flash dimensions and axial shortening were calculated on un-rotated friction welding aluminium parts. The peak temperatures were measured both in the axis and at the half-radius of the specimen. The maximum interface temperature of 581 °C for the friction weld was below the melting temperature of the aluminium alloy. The experimental and numerical results of the temperature and final weld geometries show good agreement between them. The results indicate very small deviations of 4.45%, 2.96%, and 2.34% on the flash width, flash height and axial shortening of friction welds. Full article

7xxx aluminium series reach exceptional strength compared to other industrial aluminium alloys. However, 7xxx aluminium series usually exhibit Precipitate-Free Zones (PFZs) along grain boundaries, which favour intergranular fracture and low ductility. In this study, the competition between intergranular and transgranular fracture is experimentally investigated in the 7075 Al alloy. This is of critical importance since it directly affects the formability and crashworthiness of thin Al sheets. Using Friction Stir Processing (FSP), microstructures with similar hardening precipitates and PFZs, but with very different grain structures and intermetallic (IM) particle size distribution, were generated and studied. Experimental results showed that the effect of microstructure on the failure mode was significantly different for tensile ductility compared to bending formability. While the tensile ductility was significantly improved for the microstructure with equiaxed grains and smaller IM particles (compared to elongated grains and larger particles), the opposite trend was observed in terms of formability. Full article

Aluminium metal matrix composites have been shown to make significant contributions to the area of new materials and have become widely accepted in high-tech structural and functional applications such as those in the aircraft, automobile, marine, mineral, defence, transportation, thermal management, automotive, and sports and recreation fields. Metal matrix composites are manufactured using a variety of manufacturing processes. Stirring casting, powder metallurgy, squeezing casting, in situ processes, deposition techniques, and electroplating are part of the manufacturing process used in the manufacture of aluminium-metal matrix composites. Metal matrix composites that use friction stir processing have a distinct advantage over metal matrix composites that use other manufacturing techniques. FSP’s benefits include a finer grain, processing zone homogeneity, densification, and the homogenization of aluminium alloy and composite precipitates. Most metal matrix composite investigations achieve aluminium-metal matrix composite precipitate grain refinement, treated zone homogeneity, densification, and homogenization. This part of the work examines the impact of reinforcing particles, process parameters, multiple passes, and active cooling on mechanical properties during the fabrication of 5000-series aluminium-metal matrix composites using friction stir processing. This paper reports on the available literature on aluminium metal matrix composites fabricated with 5xxx series marine grade aluminium alloy using FSP. Full article

The paper presents an analysis of the results of numerical tests of the extrusion process of structural panels made of the 5xxx and 6xxx series aluminium alloys in a designed split die. The obtained products are intended for innovative superstructures of special car bodies. The main purpose of the research was the designed split die and numerical simulations and analysis of test results to determine the parameters of the extrusion process. The distribution of stress intensity, strain, strain rate, and temperature in the extruded metal was analysed for two different speeds of the punch movement. On the basis of the analysis of the distribution of stress values occurring in the extrusion process, the conditions enabling the real process of extrusion of the panel profile in industrial conditions in the designed split die were determined. It was shown that panel sections can be produced from ingots with a length of 770 mm on a press with a pressure of 35 MN (12”). Full article

This work presents the results of the numerical and physical modelling of the hot torsion of a hardly deformable 5XXX series aluminium alloy. Studies were conducted on constrained torsion with the use of the STD 812 torsion plastometer. The main purpose of the numerical tests was to determine the influence of the accuracy of the mathematical model describing the changes in the yield stress of the tested material on the distribution of strain parameters and on the stress intensity. According to the preliminary studies, in the case of numerical modelling of the torsion test, the accuracy of the applied mathematical model describing the changes in the rheological properties of the tested material and the correct definition of the initial and boundary conditions had a particularly significant impact on the correctness of the determination of the strain parameters and the intensity of stresses. As part of the experimental tests, physical modelling of the hot torsion test was conducted. The aim of this part of the work was to determine the influence of the applied strain parameters on the distribution and size of grain as well as the microhardness of the tested aluminium alloy. Metallographic analyses were performed using light microscopy and the electron backscatter diffraction method. Due to the large inhomogeneity of the deformation parameters and the stress intensity in the torsion test, such tests were necessary for the correct determination of the so-called representative area for metallographic analyses. These types of studies are particularly important in the case of the so-called complex deformation patterns. The paper also briefly presents the results of preliminary research and future directions in which it is planned to use complex deformation patterns for physical modelling of selected processes combining various materials. Full article

During ageing, 6xxx aluminium alloys will develop a microstructure characterised by needle-shaped Mg/Si-rich precipitates in the bulk, precipitate-free zones along the grain boundaries and larger Mg/Si-rich precipitates on the grain boundary. Depending on, among other things, the size of the precipitate-free zone, these alloys are prone to intergranular fracture. The role of the grain boundary precipitates during the initiation and propagation of the intergranular fracture is still not fully understood. Transmission Electron Microscopy has been used to characterise the grain boundaries and grain boundary precipitates. The precipitates were found to be of the ${\beta }^{\prime }$ type surrounded by a layer of U2 structure. The atomic details of relevant interfaces of Al-${\beta }^{\prime }$ were characterised for further investigation. Density Functional Theory simulations were performed on the bulk precipitate structures and on the interfaces obtained experimentally. The decohesion energy of these interfaces was calculated and compared to bulk values. In addition, simulated tensile tests were performed in order to find values for the tensile strength ${\sigma }_t$. The dependence of the interfacial energy and tensile strength of ${\beta }^{\prime }$ grain boundary precipitates were found to depend on the orientation and type of interface in addition to the amount of defects on the interface. Full article

Adequate knowledge of mechanical properties and their statistical description is the basis for performing reliable verification of design methods and design of structures in general. The probabilistic design approach implemented in Eurocodes requires statistical data on all variables used in the design procedure. Although aluminium was introduced in structural Eurocodes more than four decades ago (ENV), the statistical database of mechanical properties is still inadequate. To provide a reliable statistical background, data collection was performed concerning aluminium products mainly found in the European market, within the last 20 years regarding certificates from the aluminium industry and 30 years regarding data from the research community. The collected data include aluminium alloy series 1xxx, 5xxx, 6xxx, and 7xxx, mainly extruded, and relevant mechanical properties such as 0.2% proof strength, ultimate strength, Young’s modulus, and Poisson’s ratio. They were fit to distributions, and relevant fractiles were determined, along with an analysis of nominal to characteristic and design value ratios. Variation of ratios obtained shows that that the majority of nominal values are economical and reliable. However, certain adjustments to nominal values are required to achieve a uniform reliability level in terms of the choice of alloy and temper. Full article

This research work aims at finding the optimum process parameters for the laser welding of AA7020 aluminium alloys. The use of 7xxx series alloys is limited because of weldability problems, such as hot cracking, porosity, and softening of the fusion zone despite its higher specific strength-to-weight ratio. AA7020 aluminium alloy was welded while varying the process parameters so as to obtain optimal welding efficiency. The welded samples were analysed to reveal the microstructure, defects, and mechanical properties of the welded zone. The samples were prepared from a plate of AA7020, which was hot rolled at a temperature of 470 °С to a thickness of 1 mm. The welding was carried out at an overlap of 0.25 mm, duration of 14 ms and argon shield gas flow rate of 15 L/min. Process parameters, such as peak power, welding speed, and pulse shaping, were varied. The samples were welded with Al-5Ti-B and Al-5Mg as filler metals. The welding speed, peak power, and pulse shaping have a great influence on the weldability and hot cracking susceptibility of the aluminium alloy. Al-5Ti-B improves the microstructure and ultimate tensile strength of AA7020 aluminium alloy. Full article

The results of microstructure examinations and studies of selected mechanical properties of four aluminium alloys used in the production of automotive air-conditioning ducts (AA3103, AA5049, AA6060, AA6063) before and after the ASTM G85:A3 SWAAT Test (Sea Water Acetic Acid Test) for corrosion resistance are presented. Materials used for the manufacture of such components should be temperature stable, and therefore thermal resistance tests were carried out in a wide range of temperatures, i.e., −25 °C, 25 °C, 40 °C, 60 °C, 80 °C, 100 °C, 140 °C, 180 °C, and 220 °C. Annealing was performed for 72 h and 240 h, followed by cooling in water. The obtained results have proved that the non-precipitation-hardenable AA3103 and AA5049 alloys remain stable in the entire range of the investigated temperatures. The measured microhardness of these alloys was 43–46 HV0.1 for AA3103 and 56–64 HV0.1 for AA5049. The microhardness of the 6xxx series aluminium alloys was not stable in the investigated range of temperatures. The maximum was observed in the temperature range of 100–140 °C, which corresponded to the precipitation process of intermetallic phases, as further confirmed by microstructure observations. After the corrosion test, the mechanical properties and elongation decreased by about 5–20%. Full article