Effect Of Accumulative Roll Bonding Process Research Articles

Effect of accumulative roll-bonding process on phase transformation and magnetic properties of polycrystalline cobalt

In this paper, the cobalt was deformed by accumulative roll-bonding (ARB) process. The phase transformation behavior of cobalt during accumulative rolling and its effect on the magnetic properties of polycrystalline cobalt were investigated. Twinning occurs in α-Co phase with hexagonal closepacked (HCP) structure during the ARB process, and a large number of twin boundaries hinder the phase transformation from β-Co phase to α-Co phase. {0001} texture forms in α-Co phase during rolling deformation, however, the intensity of {0001} texture decreases with the growth of twins. The coercivity of polycrystalline cobalt gradually decreases with the increasing rolling deformation, which can be attributed to the evolutions of phase and texture.

The effect of ARB process on corrosion behavior of nanostructured aluminum alloys in Na2HPO4·12H2O and Zn(NO3)2·6H2O PCMs

Phase change materials (PCMs), have high thermal energy storage due to hidden heat. One of the PCMs is hydrate salts. The insufficient long term stability of the storage materials, as containers, are the main concern in the energy storage systems which were investigated in this study. In this order, various common metals (Fine-grained Al1100 and Al6061 alloys by six cycles of accumulative roll bonding (ARB)) process were selected, and their corrosion resistance in contact with two different hydrate salts of (Na2HPO4·12H2O and Zn(NO3)2·6H2O) were tested. The immersion test method was utilized. In this way, samples were placed in the test tubes containing molten hydrate salts into a thermo-static water bath in three different periods of six, twelve and eighteen days at the temperature range of 55 to 60 °C. After each period, the sample weight loss rate was measured, and then the corrosion rate was calculated. The corrosion rate of ARBed Al 1100 and ARBed Al 6061 alloys in the Na2HPO4·12H2O at the end of eighteen days were 103.07 and 78.82 mpy, respectively. Furthermore, the corrosion rate of ARBed Al 1100 and ARBed Al6061 alloys in the Zn(NO3)2·6H2O was reported 88.67 and 68.71 mpy, respectively. The results indicated that the corrosion rate for Al1100 alloy is less and more than Al6061 alloy in the molten Na2HPO4·12H2O and molten AZn(NO3) 2·6H2O, respectively.

Microstructure, mechanical properties and electrochemical behavior of AA1050 processed by accumulative roll bonding (ARB)

In this work, the effect of ARB process on the microstructure, mechanical properties and electrochemical behavior of AA1050 was investigated. X-ray diffraction (XRD) patterns and transmission electron microscopy (TEM) images were used for measuring the crystallite and grain sizes of samples. TEM micrographs and XRD plots revealed that with increasing the number of ARB cycles, the grain/crystallite size of sample decreased and eventually nanostructured AA1050 achieved after 9 cycles of ARB with average crystallite size around 91 nm. Results of the microhardness and tensile tests demonstrated that mechanical properties of samples improved as the number of ARB cycles increased. Scanning electron microscopy (SEM) micrographs of fracture surfaces illustrated that ductile fracture occurred in all samples. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) results showed that passive behavior of the ARBed samples improves compared to the annealed AA1050 sample. Moreover, the Mott–Schottky analysis and EIS measurements showed that increasing the number of ARB cycle offer better conditions for forming the passive films.

Effect of ARB process on textural evolution of AA1100 aluminum alloy

In the present work, commercial purity aluminum strips were highly strained up to an equivalent strain of 4.8 by the accumulative roll bonding (ARB) process at ambient temperature. Furthermore, the influence of the ARB process on the development of deformation texture at the quarter thickness of ARB-processed samples was considered. ARB process leads to the formation of strong orientation along the β-fiber and also to pronounced Dillamore and Copper components. It was found that textures which were formed at ARB-processed samples were almost the same for various ARB cycles and only their intensities differ. Also, the fraction of grains with sharp high angle boundaries increased when the number of ARB cycles increased.