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![Strength to weight ratios of common aluminum and steel alloys [1].](publication/327805143/figure/tbl1/AS:673469599608834@1537579073600/Strength-to-weight-ratios-of-common-aluminum-and-steel-alloys-1.png)
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![Figure 6. Stresses in a bent sheet [4].](publication/327805143/figure/fig3/AS:673469599592450@1537579073435/Stresses-in-a-bent-sheet-4_Q320.jpg)
Today's automotive industry is increasingly adopting aluminum alloys. The main benefit of aluminum is a higher ratio of strength density compared to common steel alloys. Replacing steel with aluminum can give a weight reduction without loss of frame rigidity or crash safety. However, stamping aluminum is more difficult than steel because of its lim...
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The article examines the studies of the bayonet fragment with severe damages of metal found in the city Kremenchuk (Ukraine) in one of the canals on the outskirts of the city, near the Dnipro River. Theoretical research to study blade weapons of the World War I period and the typology of the bayonets of that period, which made it possible to put fo...
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... Currently, a range of materials, such as titanium [9-12], steels [13][14][15][16], and aluminum [17-20] alloys, have been implemented with AM techniques. Aluminum is of considerable interest due to its high strength-to-weight and stiffness-to-weight ratios, making it an attractive candidate for use with near-net-shaped processes [21][22][23]. Aluminum alloys also exhibit high reflectivity, high thermal conductivity, and a strong tendency to form surface oxides, which negatively impact the AM process and make fabricating these alloys difficult [23]. There is also an issue with the fabrication of high-strength aluminum alloys [24][25][26][27]. ...
Scalmalloy® is a novel alloy designed to work with the unique processing inherent in additive manufacturing (AM). This alloy is post-processed using a single artificial aging treatment rather than a multistep heat treatment, as often noted in traditional manufacturing processes. Much of the literature details the impact of direct aging treatments around the temperature and time recommended by the manufacturer, 325 °C for 4 h; however, few studies have explored the impact of delayed artificial aging on the resulting mechanical and microstructural behavior. This study explored this missing link and determined the impact that the time between the fabrication of the component and artificial aging has on the final properties. For this study, directed energy deposition (DED) was utilized to fabricate Scalmalloy® components. Post-processing via artificial aging was performed after fabrication to yield samples naturally aged for 0, 2, 4, 6, 8, 10, 12, and 14 days. Samples were subsequently aged at 325 °C for 4 h. Tensile testing determined that natural aging negatively impacts tensile strengths. After 6 days of delayed artificial aging (6 NA), the yield strength (YS) and tensile strength (TS) relative to day 0 (0 NA) case were diminished by 10% and 8.6%, respectively. After 12 days (12 NA), even greater property decreases were noted, with a 23% decrease in YS and an 18% decrease in TS. Microstructural characterization was performed and an increase in precipitate size and decrease in precipitate number coupled with increased grain sizes were theorized to be linked to the decrease in tensile properties. The negative impact of delayed artificial aging after AM fabrication for Scalmalloy® highlights the importance of fast transitions from deposition to heat treatment.
... Redesigning a steel item to be thicker and made of an aluminium alloy while preserving the same stiffness and crash performance may result in a 33% savings in weight. Hence, improved component design may lead to a potential weight reduction of 40-50% (Gorguluarslan et al. 2016;Feister et al. 2018;Hashim 2001;Aqida et al. 2012). Consequently, many efforts have been undertaken to enhance the mechanical characteristics including addition of reinforcing elements to form metal matrix composites (MMC) and alloying. ...
Liquid metallurgy is a cost-effective way to produce aluminium (Al) alloy products. Alloying and reinforcing in aluminium-matrix is the most practiced one in the liquid metallurgical technique, especially for mass production. Numerous developments have been observed in this technique over the past decade. This paper reviews most of the developments in processing techniques, along with providing basic information and parameters. Also, the shortcomings of each process have been significantly summarized, and potential research opportunities have been discussed. The developments in the batch and mass liquid metallurgical technique for Al have been discussed. The latest development recommendation for processing parameters and techniques to reduce the cost and time of production has been studied in detail. Based on the literature review and various published patents, the most relevant technique is a bottom-feeding continuous casting technique to produce metal matrix composites and aluminium alloys.
... 2 Among the most promising materials are aluminum (Al) and magnesium (Mg) alloys which exhibit exceptional strength to weight ratios. 2,3 However, effective protection strategies are required due to their comparably low corrosion resistance. For this reason, organic coatings are widely employed to protect light metal alloys from corrosion and to preserve the integrity of the structural material. ...
... The interlayer distance of each type of LDH decreases with lower water content as displayed by the red lines in Figure 2. The black lines illustrate the hydration energy of the LDHs with respect to different water contents. The most stable hydration state is defined by the water content corresponding to the minimum hydration energy for LDH-NO 3 − (three H 2 O per unit cell) or the water content initiating a plateau for LDH-Cl − (two H 2 O per unit cell), LDH-CO 3 2− (half H 2 O per unit cell, which equals one H 2 O per two unit cells), and LDH-C 2 O 4 2− (two H 2 O per unit cell). It is noteworthy that there is no further decrease in hydration energy when the number of water molecules per unit cell is below one for the LDH-Cl − and LDH-C 2 O 4 2− systems. ...
... 48 Its stable hydration state occurs for a half water molecule per unit cell, which was obtained by removing half of the total amount of water at the state with one water per unit cell. The interlayer distance at the most stable hydration state is the same as the experimental reference of 0.89 nm for the LDH-NO 3 − system. 49 For the LDH-Cl − system, the interlayer distance is 0.84 nm, which is slightly higher than the experimentally determined value of 0.79 nm. ...
Effective protective coatings are an essential component of lightweight engineering materials in a large variety of applications as they ensure structural integrity of the base material throughout its whole service life. Layered double hydroxides (LDHs) loaded with corrosion inhibitors depict a promising approach to realize an active corrosion protection for aluminum and magnesium. In this work, we employed a combination of density functional theory and molecular dynamics simulations to gain a deeper understanding of the influence of intercalated water content on the structure, the stability, and the anion-exchange capacity of four different LDH systems containing either nitrate, carbonate, or oxalate as potential corrosion inhibiting agents or chloride as a corrosion initiator. To quantify the structural change, we studied the atom density distribution, radial distribution function, and orientation of the intercalated anions. Additionally, we determined the stability of the LDH systems by calculating their respective hydration energies, hydrogen-bonded network connected to the intercalated water molecules, as well as the self-diffusion coefficients of the intercalated anions to provide an estimate for the probability of their release after intercalation. The obtained computational results suggest that the hydration state of LDHs has a significant effect on their key properties like interlayer spacing and self-diffusion coefficients of the intercalated anions. Furthermore, we conclude from our simulation results that a high self-diffusion coefficient which is linked to the mobility of the intercalated anions is vital for its release via an anion-exchange mechanism and to subsequently mitigate corrosion reactions. Furthermore, the presented theoretical study provides a robust force field for the computer-assisted design of further LDH-based active anticorrosion coatings.
... A possible way to overcome this is to shift the forming process to higher temperatures which increases the forming limit of the alloys [10] and prevents potential PLC effects [11]. However, this can cause negative effects such as unpredicted thinning and necking, and lower age-hardening potential [12][13][14][15]. ...
Increased formability of aluminium alloys has been demonstrated via cryogenic deformation. In previous studies, the microstructures of samples deformed at low temperatures were analysed after reheating to room temperature (RT) and storage. However, after heating the dislocation structure and density of the deformed material do not reflect the cryogenic situation. In this work, we investigate the evolution of flow stress during recovery in Al-Mg and Al-Mg-Si alloys. We examine the RT recovery behaviour of samples pre-strained at 77 K to different strain levels, and evaluate the structural stability upon subsequent deformation. We also study microstructural evolution via in-situ synchrotron X-ray diffraction, starting from initial conditions at cryogenic temperatures to long-term RT-recovery. Recovery of cryogenically deformed samples at RT results in reduction of the flow stress, in dependence on RT storage. The recovery process can be divided into three distinct sections, each based on a different mechanism characterized by either the arranging or the annihilation of dislocations. Subsequent further straining at room temperature after cryogenic forming also generates plastic instabilities and premature fracture due to unfavourable hardening and recovery assisted softening interplay.
... A possible way to overcome this is to shift the forming process to higher temperatures which increases the forming limit of the alloys [10] and prevents potential PLC effects [11]. However, this can cause negative effects such as unpredicted thinning and necking, and lower age-hardening potential [12][13][14][15]. ...
Production of complex lightweight parts for transport applications requires a high level of formability. This has been shown to be achievable via deep-drawing of aluminium alloys at cryogenic temperatures. Although the effect of an extended plastic deformation regime at low temperature is well known, the mechanisms behind it are unclear due to the limits of the characterisation methods applied. In previous studies, the microstructures of samples deformed at low temperatures were examined after reheating to room temperature (RT) and storage. However, after heating the dislocation structure and density of the deformed material change and do not reflect the cryogenic situation. In this work, we investigate the evolution of flow stress during recovery in Al-Mg and Al-Mg-Si alloys. We examine the RT recovery behaviour of samples pre-strained at 77 K to different strain levels, and evaluate the structural stability upon subsequent deformation. We also study microstructural evolution via in-situ synchrotron X-ray diffraction, starting from initial conditions at cryogenic temperatures to long-term RT-recovery. Recovery of cryogenically deformed samples at RT results in reduction of the flow stress, in dependence on RT storage. The recovery process can be divided into three distinct sections, each based on a different mechanism characterised by either the arranging or the annihilation of dislocations. Subsequent further straining at room temperature after cryogenic forming also generates plastic instabilities and premature fracture due to unfavourable hardening and recovery assisted softening interplay.
... Feister et al. [8] obtained FLC curves of 7075-T6 material at different temperatures and used it in finite element analysis. It is shown that the formability increases with increasing of the temperature. ...
Thanks to their low density and high strength, the 7XXX series aluminum alloys are widely used as a support/beam parts in the aerospace industry. This alloy is target in the lightening studies of the automotive industry and surveys for sheet metal are still in progress. It is a series of alloys that can be applied to the aging process and has the most effect on mechanical properties. As formability is quite weak, methods are investigated. In this study, tensile test, bending test and Erichsen tests are performed at different deformation rates and temperatures. As a result of the experiments, it has been seen that the formability increases at high temperature and low deformation rates. If paint baking time is long, there will be no loss of strength. Also, the bending process is modeled with the help of the finite element analysis programs and the springback estimations are examined. It is seen that the results of the modeling process are quite successful. The effect of the strain rate sensitivity is determined.
Variations in the warm formability of AA7075 sheets are primarily attributed to differences in precipitate morphology resulting from distinct thermal histories. To better understand this relationship, this study systematically investigates the influence of precipitate characteristics—quantified by the product of precipitate volume fraction and average radius—on forming limits across various thermal routes in warm forming processes. A modified Cockcroft–Latham ductile fracture model incorporating this microstructural parameter was developed, calibrated against experimental data from warm isothermal Nakajima tests, and implemented within a finite element framework. The proposed model enables the accurate prediction of forming limit curves with minimal experimental effort, thereby significantly reducing the reliance on extensive mechanical testing. Building upon the validated FE model, a practical methodology for rapid R-value estimation under warm forming conditions was established, involving the design of specimen geometries optimised for isothermal Nakajima testing. This approach achieved R-value predictions within 5% deviation from conventional uniaxial tensile test results. Furthermore, experimental results indicated that AA7075 sheets exhibited nearly isotropic deformation behaviour under retrogression warm forming conditions. Overall, the methodology proposed in this study bridges the gap between formability prediction and process simulation, offering a robust and scalable framework for the industrial optimisation of warm forming processes for high-strength aluminium alloys.
AA7075-T6 sheets with 1, 1.5, and 2 mm thicknesses were tailor-welded using the gas tungsten arc welding process. The welded blanks were solution heat treated, hot stamped, and simultaneously quenched to produce U-shaped components, and finally artificially aged. A finite element model using the ABAQUS software was developed to simulate the forming process. The experimental and numerical results showed no rupture in the components. Tensile and hardness tests revealed that the maximum tensile strength, yield strength, and microhardness of the aged specimen were approximately 96%, 93%, and 107% of the initial material, respectively. Maximum and minimum microhardness of 196 and 145 HV were observed in the heat-affected and fusion zones of the specimens, respectively. Increasing the tailoring ratio increased the strengthening behavior of the components. With a tailoring ratio of 1, the maximum and minimum elongations at break were 70% and 40% of the original aluminum sheet for 2 mm and 1 mm thick sheets, respectively.
Metal matrix composites with superior mechanical and fatigue properties are in great industrial demand. In the present study, a two-step stir casting method and T6 heat treatment were implemented to fabricate Al7075-SiC composites. SiC particles of varying content and size (nano, submicron, and micron) were added to the Al7075 matrix. Tensile strength and fatigue properties of the fabricated composites were then evaluated. Results showed that addition of SiC particles into the matrix increased tensile and fatigue strength. In contrast, the elongation of samples decreased. Samples reinforced with nanoparticles showed better tensile and fatigue properties compared with the other composites (submicron and micron reinforcement). It was observed that Al7075 reinforced with 1% weight percentage of SiC nanoparticles improved the ultimate tensile strength and fatigue strength of pure Al7075 samples by 21.33% and 66%, respectively. However, further addition of reinforcing particles above a certain limit resulted in a decrease in tensile strength.
