Preparation of ultrafine-grained twin-roll cast AlMg3 sheets by accumulative roll bonding

Accumulative Roll Bonding (ARB) is a technique of grain refinement by severe plastic deformation, which involves multiple repetitions of surface treatment, stacking, rolling, and cutting. The rolling with 50% reduction in thickness bonds the sheets. After several cycles, ultrafine-grained (UFG) materials are produced. Since ARB enables the production of large amounts of UFG materials, its adoption into industrial practice is favoured. ARB has been successfully used for preparation of UFG sheets from different ingot cast aluminium alloys. Twin-roll casting (TRC) is a cost and energy effective method for manufacturing aluminium sheets. Fine particles and small grain size are intrinsic for TRC sheets making them good starting materials for ARB. The paper presents the results of a research aimed at investigating the feasibility of ARB processing of three TRC alloys, AA8006, AA8011 and AA5754, at ambient temperature. The microstructure and properties of the ARB were investigated by means of light and transmission electron microscopy and hardness measurements. AA8006 specimens were ARB processed without any problems. Sound sheets of AA8011 alloy were also obtained even after 8 cycles of ARB. The AA5754 alloy suffered from severe edge and notch cracking since the first cycle. The work hardening of AA8006 alloy saturated after the 3rd cycle, whereas the hardness of AA5754 alloy increased steadily up to the 5th cycle. Monotonous increase in strength up to 280 MPa was observed in the ARB processed AA8011 alloy.

Download Full-text

Annealing Effects in Twin-Roll Cast AA8006 Aluminium Sheets Processed by Accumulative Roll-Bonding

Materials ◽

10.3390/ma7128058 ◽

2014 ◽

Vol 7 (12) ◽

pp. 8058-8069 ◽

Cited By ~ 2

Author(s):

Miroslav Cieslar ◽

Michaela Poková

Keyword(s):

Accumulative Roll Bonding ◽

Roll Bonding ◽

Annealing Effects ◽

Aluminium Sheets ◽

Twin Roll Cast ◽

Twin Roll

Download Full-text

Accumulative roll-bonding: first experience with a twin-roll cast AA8006 alloy

Journal of Alloys and Compounds ◽

10.1016/j.jallcom.2003.10.082 ◽

2004 ◽

Vol 378 (1-2) ◽

pp. 322-325 ◽

Cited By ~ 21

Author(s):

M. Karlı́k ◽

P. Homola ◽

M. Slámová

Keyword(s):

Accumulative Roll Bonding ◽

Roll Bonding ◽

Twin Roll Cast ◽

Twin Roll

Download Full-text

Effect of the Temperature of Accumulative Roll Bonding on the Microstructure and Properties of Twin-Roll Cast AA8006 Alloy

Materials Science Forum ◽

10.4028/www.scientific.net/msf.503-504.281 ◽

2006 ◽

Vol 503-504 ◽

pp. 281-286 ◽

Cited By ~ 4

Author(s):

Petr Homola ◽

Margarita Slámová ◽

Miroslav Karlík ◽

Jakub Čížek ◽

Ivan Procházka

Keyword(s):

Accumulative Roll Bonding ◽

Positron Annihilation Spectroscopy ◽

Tensile Tests ◽

Special Equipment ◽

Roll Bonding ◽

Fine Grained ◽

Transmission Electron ◽

Number Of Cycles ◽

Twin Roll Cast ◽

Twin Roll

Accumulative Roll Bonding (ARB) does not require any special equipment and enables the production of large amounts of ultra-fine grained (UFG) materials. Grain refinement is thermally stable in materials with finely dispersed particles such as twin-roll cast (TRC) aluminium alloy sheets, favourable materials for manufacturing UFG sheets. The results of a study of the effect of ARB temperature on bonding quality, structure and properties of TRC AA8006 sheet are presented. Examinations by light and transmission electron microscopy, positron annihilation spectroscopy (PAS), hardness and tensile tests were used in the study. After two cycles at 200°C, mean grain size of 0.4 - 0.8 μm is achieved, but areas with extremely fine grains of 0.1 to 0.3 μm in diameter are also observed. Hardness increases significantly after two cycles and it rises a little in subsequent cycles. Processing at higher temperatures (up to 350°C) results in better bonding but it produces smaller increase in hardness. Significant increase of dislocation density is observed by PAS after the first cycle at 250°C but it does not continue during subsequent cycles. Partial recrystallization occurs in samples processed at temperatures above 250°C explaining the smaller increase in hardness. Softening level depends on both ARB temperature and number of cycles. The thermal stability of refined structures produced by ARB at 250°C is better than these formed at higher temperatures.

Download Full-text

Effect of the Temperature of Accumulative Roll Bonding on the Microstructure and Properties of Twin-Roll Cast AA8006 Alloy

Materials Science Forum - Nanomaterials by Severe Plastic Deformation ◽

10.4028/0-87849-985-7.281 ◽

2006 ◽

pp. 281-286

Author(s):

Petr Homola ◽

Margarita Slámová ◽

Miroslav Karlík ◽

Jakub Čížek ◽

Ivan Procházka

Keyword(s):

Accumulative Roll Bonding ◽

Roll Bonding ◽

Microstructure And Properties ◽

Twin Roll Cast ◽

Twin Roll

Download Full-text

Influence of homogenization on the microstructure, mechanical properties and texture of the twin-roll cast AA8006 sheet processed by accumulative roll-bonding

MATEC Web of Conferences ◽

10.1051/matecconf/202032605003 ◽

2020 ◽

Vol 326 ◽

pp. 05003

Author(s):

Miroslav Karlík ◽

Petr Homola ◽

Peter Sláma ◽

Jiří Čapek ◽

Petr Harcuba

Keyword(s):

Mechanical Properties ◽

Accumulative Roll Bonding ◽

Rolling Texture ◽

Tensile Tests ◽

Grain Structure ◽

Electron Backscattered Diffraction ◽

Roll Bonding ◽

Fine Grain ◽

Twin Roll Cast ◽

Twin Roll

Unhomogenized and homogenized AA8006 (Al-Fe-Mn-Si) alloy sheets twin-roll cast to strip 8.5 mm thick, processed by accumulative roll-bonding (ARB) on 2 mm thick sheets up to 6 cycles were studied. The microstructure was characterized by means of scanning and transmission electron microscopy and electron backscattered diffraction (EBSD), mechanical properties were monitored by hardness measurements and tensile tests. The macroscopic texture was determined by X-ray diffraction. The initial texture of the unhomogenized sheet is rotated cubic {001}<110> combined with recrystallization R texture {011}<211>, while the homogenized sheet has a cubic texture {001}<100> with remaining rolling component C {112}<111>. One ARB cycle leads to the formation of low-angle grain boundaries (LAGB) in original coarser grains and to a low angle rotation of the subgrains bounded by LAGB. After the 3rd and 6th ARB cycle unhomogenized and homogenized sheets show a common rolling texture of cold-rolled aluminium. The thermal stability of sheets processed by 6 ARB cycles was tested by isochronal annealing for 30 min up to 450°C. The homogenized sheet starts to recrystallize at 250°C, while the fine grain structure of the unhomogenized sheet is thermally stable up to 400°C.

Download Full-text

Mechanical Properties and Aging Behavior of Ultrafine Grained Al-Ag Alloy Fabricated by Accumulative Roll-Bonding

Materials Science Forum ◽

10.4028/www.scientific.net/msf.794-796.851 ◽

2014 ◽

Vol 794-796 ◽

pp. 851-856

Author(s):

Tadashiege Nagae ◽

Nobuhiro Tsuji ◽

Daisuke Terada

Keyword(s):

Mechanical Properties ◽

Grain Refinement ◽

Accumulative Roll Bonding ◽

Precipitation Hardening ◽

Tensile Elongation ◽

Solution Treatment ◽

High Strength ◽

Subsequent Aging ◽

Roll Bonding ◽

Ultrafine Grained

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.

Download Full-text