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Accumulative roll bonding simulation dating, article versions

With respect to grain refinement, IHT is counter-productive, as it may cause recovery, recrystallization and grain growth. The increasing number of phase boundaries is beneficial for two reasons.

When co-deformation is applied repetitively, as is the case for accumulative roll bonding ARB [ 262728 ] and for accumulative swaging and bundling ASB [ 162930313233 ], the density of phase boundaries increases with applied bonding or bundling cycles, respectively.

In both cases, the ultrafine grains were developed in the samples.

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The roll peripheral speed of one roll was 2. The softening behavior and enhanced ductility was explained by dynamic recovery, the recrystallization process and even abnormal large grains. Consequently, a highly strengthened light weight material cannot be achieved with this procedure.

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Once the Ti layers are strain hardened beyond a certain limit, their formability is negligible when compared to the Al sheets. Marion Merklein, Uwe Vogt Abstract: In contrast to a four high rolling mill, which is symmetric with respect to the sheet plane, trio rolling with different sizes of the upper and lower rolls is asymmetric.

Layer continuity in accumulative roll bonding of dissimilar material combinations

The ARB cycles were repeated up to eight times. Results show that even though both the microhardness and tensile strength go up with increasing deformation, they are not related to each other by a factor of 3.

Alternatively, the arrangement of rolls and the geometry of the rolling gap can be altered. In contrast accumulative roll bonding simulation dating this, the individual Ti and Al layers remain stable when an intermediate heat treatment IHT is applied between the rolling cycles.

In addition, it is necessary to emphasize that the individual layers become wavy with increasing deformation strain, i. When applied in combination, these hardening mechanisms may even have a synergetic strength effect. These materials also show considerable strength at elevated temperatures when grain growth occurs in at least one phase, as grain growth is limited to the distance of the phase boundaries.

However, the reduction of strength with rising temperature is less pronounced in Ti than in Al.

Application of Accumulative Roll Bonding Process for Manufacturin Ingenta Connect

Mapping solution, a remeshing analysis technique, was adopted to transfer the deformation solution from the deformed mesh to a new mesh between cycles, which not only enabled the simulation of discontinuous processes, but also alleviated the mesh distortion.

The elongation was not affected significantly by the number of ARB cycles in both cases. In this study, a finite element model was proposed and by which the real ARB process was successfully simulated for 5 cycles for the first time. However, this is not possible to apply to the composite, as this temperature is above the melting temperature of Al.

During the first ARB cycle, these conditions are met, but already for the second cycle, the work hardening ability of Ti is already saturated and, thus, may be responsible for the necking of the Ti layers.

Moreover, with this technique, tensile tests of ARB processed materials were also simulated. At elevated temperatures, successful roll bonding of Al can be achieved using a lower thickness reduction.

A better distribution of the second phase and an increase in solid solubility are also observed after ARB. A crucial issue is to retain individual continuous layers within the composite during accumulative deformation.

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The ARB was conducted up to 6 cycles at ambient temperature without lubrication. Co-deformation of two metallic materials, such as Al and Ti, bears the potential to gain improved material properties regarding strength and formability. The variation of the elongation with the cycle number coincided exactly with the variation of grain size at the center of the processed plate.

The size of grains at the top and bottom of the rolled plate converged to 0. Materials Science and Engineering: The distribution of hardness was in the same pattern as equivalent plastic strain through the thickness at first and then it tended to be uniform due to microstructural saturation.

Secondly, these phase boundaries limit possible grain growth.

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Even in the case when the excenter velocities of the upper and lower rollers are identical, the difference in diameter causes shearing in the deformation zone and, thus, eases bonding and reduces necking. Whereas the grain-refinement causes a drastically increased strength of the aluminum material, the formability of the ARB-blanks made of industrially used aluminum alloys such as the AA deteriorates to the same degree as the strength rises.

Layer continuity in accumulative roll bonding of dissimilar material combinations

Usually the heat treatment in the cyclic ARB passes is indispensable to reduce work-hardening effects and improve interface bonding quality. The roll speed ratio was kept at 1. The deformation behaviours, in terms of texture, hardness, tensile strength and fracture, and plasticity instability were studied.

Summarizing, high densities of grain and phase boundaries significantly contribute to the strength of metallic composites.

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Both material properties are strongly linked to the microstructure. The highest values of these parameters depend more on the initial microstructure than on the total deformation. Texture analysis demonstrated that the shear strain, in the case of DSR-ARB, was introduced into the center of thickness.

The high shear stresses during the rolling cycles result in an ultrafine-grained microstructure with an average grain size ranging between to nm.

Accumulative roll bonding

After deformation to very large plastic strains, the multi-phased materials have a mean phase boundary distance in the the sub-micrometer-range. Nano-structured aluminum was fabricated by accumulative roll-bonding ARB process using different rolling methods.

Severe plastic deformation processes are used to refine grain structure by means of very high deformations.