Papers by Keyword: Accumulative Roll Bonding (ARB)

Abstract: Composite materials were applied to meet the demands of production efficiency on industrial because they offered the superior properties both of aspects on mechanical and physical properties were constantly being refined and developed with several methods. Composite technology with aluminum as a matrix as well as ceramic materials as reinforcement was very dependent on a result of the perfection of the manufacturing process on the matrix material and reinforcement was used. Aluminum currently still dominates as a matrix because of its ductility, while reinforcing materials that are widely used are ceramic elements such as silicon carbide (SiC) and alumina (Al₂O₃). Using of SiC/Al₂O₃ has been widely studied because of the remarkable improvement of the mechanical properties it produces. The addition of number of SiC particles to Al₂O₃ was able to significantly increase the hardness properties. In this study, a number of composite manufacturing methods were compared from the results of properties by accumulative press bonding (APB), accumulative roll bonding (ARB), and repetitive press roll forming (RPRF). The mechanical properties of RPRF results are known to produce better properties, especially mechanical properties. Mechanical properties were observed from tensile and hardness tests. The finer grain size is produced by increasing the compression cycle and increasing the mechanical properties when adding double reinforcement of the SiC/Al₂O₃, which causes the strength and hardness of the RPRF results to increase. Whereas other methods such as APB and ARB it is not compatible with composite materials, this proves that the RPRF method was very suitable for processing composite materials compared to APB and ARB methods.

Abstract: Al/Ni composite is widely recognized as a member of multifunctional energetic structural materials (MESMs), which could release energy due to exothermic chemical reactions initiated under shock loading conditions. In this study, an Al/Ni composite was produced via accumulative roll-bonding (ARB) process up to four cycles. The shock-induced reaction behavior of the material was investigated by means of a quasi-sealed test chamber. The results demonstrated that the Al/Ni composite fabricated by ARB underwent chemical reaction when impacted onto steel target. The energy released by reaction caused significant pressure rise inside the quasi-sealed chamber. It was shown that the amount of energy increased with the increasing of impact velocity. The results of this study represented the potential of Al/Ni composite processed by ARB as reactive fragments.

Abstract: Microstructure and texture evolution of commercially pure Ni processed by accumulative roll-bonding (ARB) up to eight cycles were studied using electron back scattered diffraction (EBSD). During ARB processing, the original coarse equiaxed grains were gradually transformed into refined lamellar grains along the rolling direction (RD). Shear bands started forming after three cycles. The fraction of low angle grain boundaries (LAGBs) increased after the first and second cycle because of orientation spreading within the original grains. However, their fraction decreased with the evolution of high angle grain boundaries (HAGBs) during subsequent deformations, until saturation was reached after six cycles. Overall, the typical deformation texture components (S, Copper and Brass) were enhanced up to six ARB cycles and then only Copper was further strengthened. At higher cycles a higher Copper concentration was found near sample surface than the interiors due to a high frictional shear of ARB processing.

Abstract: Mg/Al alloy multilayered composites were produced by accumulative roll bonding (ARB) technique. The microstructures of Al and Mg alloy layers were characterized by scanning electron microscopy, and damping capacity of the composite was tested by dynamic mechanical analyzer.It can be found that the diffusion layers were produced in Al and Mg alloy layers, and the diffusion layers increased with increasing of the ARB pass. With the increasing of ARB pass, the room temperature damping value of Mg/A1 multilayered composite presented a downward trend. The temperature damping spectrum of the composite had two internal friction peaks, with the increasing of the ARB pass, the peak height of P1 peak increased gradually and P2 peak moved to low temperature gradually.

Abstract: Aluminium metal matrix composites reinforced with WC ceramic particles were manufactured through warm accumulative roll bonding (ARB) in this study. The microstructures of the composites exhibited excellent particles distribution in the matrices. Compared with the mechanical properties of ARB monolithic pure Al, the Al/WC composites exhibited higher tensile strength. The shear lag theory modified was used in considering the yield strength of the composites. The results indicated that the effects of WC particles in Al/WC composite lead to the thermal expansion dislocation strengthening, small subgrain strengthening, Orowan strengthening and geometrically necessary dispersion strengthening.

Abstract: The grain size dependence of creep behavior from coarse grain to ultrafine grain regions was examined using fully-annealed specimens fabricated from a single process route. For coarse-grained sample, in tensile deformation, stress-strain curves show slow work hardening, and the proof stress shows typical Hall-Petch behavior. On the other hand, creep behavior is observed under the stress above the proof stress, and the creep rate has no grain size dependence. For ultrafine-grained sample, in the tensile deformation, stress-strain curves show yielding behavior, and the yield stress shows Hall-Petch behavior also. On the other hand, creep behavior was observed below the proof stress, but the creep rate decreases with a decrease in grain size.

Abstract: Accumulative roll-bonding (ARB) process is one of the severe plastic deformation processes for fabricating ultrafine grained materials that exhibit high strength. In aluminum alloys, aging heat treatment has been an important process for hardening materials. In order to achieve good mechanical properties through the combination of grain refinement hardening and precipitation hardening, an Al-4.2wt%Ag binary alloy was used in the present study. After a solution treatment at 550°C for 1.5hr, the alloy was severely deformed by the ARB process at room temperature (RT) up to 6 cycles (equivalent strain of 4.8). The specimens ARB-processed by various cycles (various strains) were subsequently aged at 100, 150, 200, 250°C, and RT. The hardness of the solution treated (ST) specimen increased by aging. On the other hand, hardness of the ARB processed specimen decreased after aging at high temperatures such as 250°C. This was probably due to coarsening of precipitates or/and matrix grains. The specimen aged at lower temperature showed higher hardness. The maximum harnesses achieved by aging for the ST specimen, the specimens ARB processed by 2 cycles, 4 cycles and 6 cycles were 55HV, 71HV, 69HV and 65HV, respectively. By tensile tests it was shown that the strength increased by the ARB process though the elongation decreased significantly. However, it was found that the tensile elongation of the ARB processed specimens was improved by aging without sacrificing the strength. The results suggest that the Al-Ag alloy having large elongation as well as high strength can be realized by the combination of the ARB process for grain refinement and the subsequent aging for precipitation hardening.

Abstract: The Accumulative Roll Bonding (ARB) process enables the manufacturing of high strength sheet metals with outstanding mechanical properties by repeated rolling. However, the significant increase in strength leads to loss in ductility, especially regarding aluminum alloys of the 6000 series. The low formability obviously limits the implementation of these sheet products for formed components in automotive applications. To enhance formability, a local short term heat treatment according to the Tailored Heat Treated Blanks technology is used. For the finite element based design of forming operations accurate information about the plastic behavior of these tailored materials is required. Therefore, different stress - strain paths are considered using the tensile test and the layer compression test. In this context, heat treated and non-heat treated specimens out of ARB processed AA6016 were tested at room temperature. With the experimental results true stress strain curves and yield loci determined from different criteria and represented in a principal stress state were established. Regarding the experimental setup of the ARB process, an upscaling is essential for the production of sufficiently large strips to cut out blanks for the forming of components such as B-pillars. However, this requires the adaptation of the different process steps of the ARB process. In this context, the surface treatment before rolling of such large sheets is investigated, since it is particularly relevant for obtaining a strong bonding between the sheets. Another aspect is the investigation of the rolling process using the finite element analysis. In this regard, a thermal mechanical coupled simulation model of the roll bonding operation will be developed for the evaluation of different material combinations, different process temperatures and varying roller geometries. These investigations will enable the production of lightweight automotive components made of ARB processed high strength aluminum sheet metal with tailored properties.

Abstract: In this work the influence of accumulative roll bonding (ARB) process on the microstructure and the mechanical characteristic is investigated. Therefore, AZ31 magnesium sheets were successfully deformed through ARB for a maximum of three passes. Twin roll cast sheets and twin roll cast sheets with subsequent heat treatment (480 °C, 1 h) were used as initial materials. After one ARB pass, the highest microstructure changes were measured. Electron backscattered diffraction (EBSD) reveals a bimodal microstructure with an average grain size of ~1µm. In comparison to the initial material a strong basal texture was measured. The significant refinement of grain size after severe plastic deformation cause an increase of tensile and compressive strength, e.g. rising yield stress and ultimate tensile strength of 42% and 15%, respectively. However, the maximum formability remains nearly at the same level. Further ARB passes do not improve the mechanical characteristics further.

Abstract: Accumulative Roll-Bonding (ARB) process is a severe plastic deformation (SPD) process, capable of developing grains below 1 μm in diameter and improving mechanical properties of the material. In this study, the authors compared two different FE-codes with respect of its applicability for numerical analysis of the ARB process. Modelling this process was achieved using the explicit code for Abaqus/CAE both in 2D and 3D. The proposed model was used to assess the impact of ARB cycles on the final material properties. The numerical results in 2D and 3D were compared and contrasted. The research work presented in this paper is focused on the simulation optimization based on CPU time minimization. The numerical simulations were also validated through a comparison with the experimental results.