Papers by Keyword: Aluminum Alloy

Abstract: Wire arc additive manufacturing (WAAM) stands out as a highly promising direct energy deposition (DED) technology for producing large-scale metallic parts, primarily due to its efficiency, high deposition rate, and low production costs. WAAM can be exploited with many advantages to a wide range of metallic materials, including aluminum, copper, and magnesium. This paper deals with the examination of thermal cycles and temperature fields developed during additive manufacturing of an AA5087 aluminum alloy part using conventional Cold Metal Transfer (CMT) with variable deposition parameters. The thermal cycles were experimentally measured by an Ahlborn Almemo 5690-2 measuring station equipped with K-type thermocouples. A simulation model of the deposition process was developed to perform a more detailed study of the impact of the travel speed on the temperature distribution and geometrical characteristics of single weld beads, using ANSYS software. The measured and computed thermal cycles and peak temperatures reached during the 1^st and 2^nd deposition cycle were compared. The maximum measured temperatures at a travel speed of 25 cm/min were 503.4 °C (1^st cycle) and 419.6 °C (2^nd cycle), while the calculated temperatures were 502.5 °C and 417.4 °C, respectively. At a higher travel speed of 35 cm/min, the peak temperatures were lower, with experimental values of 459.6 °C (1^st cycle) and 417.5 °C (2^nd cycle), and calculated values of 459.0 °C and 391.2 °C.

Abstract: Aluminum alloys are known for their wide application in the automotive, river and marine boat constructions, but also in hydraulic systems (radiators/oil coolers). Their use is made by manufacturing parts directly from the semi-finished state, with or without certain volumetric heat treatments and surface hardening, depending on the functional role and the physical-mechanical characteristics pursued. Some of these parts work in hydrodynamic conditions, where cavitation manifests itself through erosion, such as: propellers of boats and barges, pump rotors in water cooling systems of automobiles. Visual analyzes performed on sailboat and powerboat propellers, after identical durations and operating conditions, showed cavitation erosion damage, different depending on the type of aluminum alloy. As a result, the paper presents and analyzes the behavior and resistance to erosion by vibratory cavitation of 4 types of aluminum alloys in the state of rolled semi-finished products. To highlight the differences in the destruction of structures under the cyclic stresses of cavitational microjets, macro and microscopic images of the eroded structure are used, as well as the curves with the values of the parameters specific to cavitation, recommended by the ASTM G32 -2016 norms and used in the research laboratory's custom. The analysis of the results shows that the resistance of the structure to cavitation erosion is dependent on the type of alloy, the degree of brittle intermetallic compounds and the mechanical properties specific to toughness.

Abstract: The microstructure evolution during the extrusion process of AA6XXX aluminum alloys is getting a significant interest from extruders and researchers because of the effect of the grain structure on the extruded component properties. Several process and material parameters such as chemical composition, homogenization, temperature evolution, extrusion speed, geometries and quenching have a direct impact on the final grain size of extruded profiles. Because there are so many affecting elements, it is extremely challenging to forecast the microstructure evolution and, as a result, research activities are still required to understand and control the aluminum alloy recrystallization behaviour. In this work, a methodology for the microstructural characterization of AA6XXX aluminum alloys is proposed. The methodology involves the experimental investigation of the profile grain evolution during the extrusion process, the development of a AA6XXX recrystallization model optimized to describe the AA6063 recrystallization behaviour and the simulation by means of finite element method of the final microstructure of the extruded profile.

Abstract: In this study, the corrosion behavior of aluminum alloy was investigated in graphene nanoplatelet (GNP) nanofluids prepared with different surfactants. The surfactants include sodium dodecylbenzene sulfonate (SDBS), sodium dodecyl sulfate (SDS), Tween 80, and Gum Arabic (GA). The corrosion properties of the alloy in the different GNP nanofluids were evaluated using potentiodynamic polarization tests at room temperature. The surface morphology of the aluminum alloy was analyzed using a scanning electron microscope coupled with an electron dispersive spectroscopy detector. The experimental results revealed that the addition of surfactants improves the resistance of the aluminum alloy to corrosion in the nanofluid. This was attributed to the adsorption of surfactants on the surface of the alloy to form a protective film layer, which reduces moisture permeability and enhances corrosion inhibition. The addition of GA was found to exhibit the highest inhibition efficiency. This was followed by Tween 80, SDS, and SDBS, which contributes the least inhibition. XRD post-corrosion analysis also reveals the presence of aluminum oxide and aluminum hydroxide phases on the surface of electrodes immersed in all the different GNP nanofluids.

Abstract: The piston connecting rod is an indispensable in the internal structure of the automobile. As one of the important components in the internal combustion engine system, the piston connecting rod needs to meet the requirements of high fatigue and impact load resistance. Forged piston connecting rod can obtain high strength and fatigue resistance. In this study, the parting line, draft angle, forging tolerance, die fillet radius, shrinkage and scrap are considered in the design of forging die. The process parameters and die dimensions of the forging process of aluminum alloy piston rod are simulated by finite element analysis. The aluminum alloy piston rod with high dimensional accuracy is then forged according to the finite element simulation results.

Abstract: The Swiss-type automatic lathe is designed for continuous mass production of the same product. In the research, the authors propose a combined turning process in which a joining process using the frictional welding method is introduced into the automatic lathe. If the joining process is performed with a Swiss-type automatic lathe, it is expected that the problem of a large amount of residual material due to the mechanical structure can be solved. Generally, the friction welding method is performed by a dedicated machine and is pressure controlled by a hydraulic power source, however in the case of an automatic lathe, friction welding is controlled by the feed length and feed rate. The low rigidity of automatic lathes is also concerned. In the study, the authors investigated the tensile strength and rotational bending fatigue strength of the A6061 bonding material to investigate and quantitatively evaluate the optimum friction welding conditions that can obtain good bonding results in the friction welding method using a multi-axis automatic lathe. Upset speed was the most influential factor for tensile strength and friction rotation speed was good at about 4000 rpm. This fact suggests that excessive heat input leads to a decrease in tensile strength. The tensile strength was equivalent to that of the annealed material. It also seems that the air-cooled annealing phenomenon occurs during the friction welding process. The results of rotational bending fatigue strength were similar to those of the annealed material. It is clarified that friction welding with an automatic lathe is feasible, however, the strength of the bonded material is reduced to the same level as that of the annealed material.

Abstract: Incremental Sheet Forming (ISF) is emerging as one of the popular dieless forming processes for the small-sized batch production of sheet metal components. However, the parts formed by the ISF process suffer from poor surface finish, geometric inaccuracy, and non-uniform thinning, which leads to poor part characteristics. This paper deals with the influence of single point continuous local forming process parameters on the surface roughness of the product. Design of trials used for research planning and analysis and interpretation of results. The results indicate that the tool diameter (D), vertical step-down size (Δz), and sheet thickness (t) have significant effects on the produced profile accuracy, while the feed rate (f) is not significant. As a general rule, thin sheets with greater tool diameters yielded the best surface quality. The results also show that controlling all surface quality features is complex because of the contradicting effects of, and interactions between, a number of the process parameters.

Abstract: In this study, the heat transfer coefficients of 7050 aluminum alloy under different water temperatures, polyalkylene glycol aqueous solution concentrations and quenching medium types are calculated by an iterative method, and the heat transfer coefficient of the aluminum alloy under different quenching medium parameters was compared and the difference was discussed in detail. The results show that with the increase of water temperature, the heat transfer coefficient of 7050 aluminum alloy gradually decreases; with the increase of polyalkylene glycol aqueous solution concentration, the heat transfer coefficient gradually decreases; the order of heat transfer capacity of quenching medium is disclosed among the studied medium types.

Abstract: Tensile tests on AA5005 alloy were conducted on model MTS-810 tensile test machine during temperature 633-773 K and strain rate 0.0003-0.03 s^-1. The flow stress–true strain curves were obtained. In order to analyze the flow stress behavior of aluminum AA5005 alloy, the phenomenological Fields-Backofen equation based on the fitting regression analysis was developed. The flow stress values calculated by the obtained model keep coincidence with experimental values. Eventually, the statistical analysis methods (correlation coefficient (R), average absolute relative error (AARE)) were adopted to examine the credibility of the established model. Results show that the R-value is 0.99592 and the AARE is 3.3128 %, which indicates the high fitting accuracy of the Fields-Backofen equation. Consequently, the Fields-Backofen model can describe the constitutive relationship of AA5005 alloy credibly.

Abstract: The 7020-aluminum alloy is a lightweight and high strength material which is widely used in aerospace industries where the damage tolerance, the factor of safety and environmental induced fatigue is very high. The low density and better mechanical properties enable its applications in industries over conventional engineering materials. In the present work, the fatigue crack growth (FCG) behavior of the pre-corroded 7020-aluminum alloy was investigated. The samples were subjected to an aqueous solution of sodium chloride; the micro-hardness was optimized and the significance of corrosion on FCG was studied in the context of bending stress, the number of cycles (N) to failure/fatigue life and microstructure. The solution treated samples at a temperature of 520°C for 3 hours provided the maximum hardness. However, the hardness of samples was optimum for 3 hours of solution heat treatment and minimum for 2 hours of solution heat treatment. It is suggested that the precipitation of the metastable phase affected the hardness. In the initial stage, the fatigue life of pre-corroded samples was significantly lower as compared to as-received samples. However, at the later stage, it became less significant but still, the pre-corroded sample showed lower fatigue life. Both types (pre-corroded and as-received) of samples showed a similar trend as fatigue life decreases with increasing bending stress. The fractured microstructure of the pre-corroded sample showed scratches on the surface which were produced during mechanical rubbing of the specimen pieces during plastic deformation under load. However, the microstructure at the edge of the notch showed "volcano-mouth" features" which indicated the phenomena of galvanic corrosion. The galvanic corrosion envisages due to deposition on the 7020-aluminum alloy and the impurities in the alloy. The elements Fe, Si, C and Mn existed as impurities that induced the galvanic corrosion and an elliptical corrosion pit was observed.