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

2004 ◽  
Vol 378 (1-2) ◽  
pp. 322-325 ◽  
Author(s):  
M. Karlı́k ◽  
P. Homola ◽  
M. Slámová
Keyword(s):  
Accumulative Roll Bonding ◽  
Roll Bonding ◽  
Twin Roll Cast ◽  
Twin Roll

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

2006 ◽  
Vol 503-504 ◽  
pp. 281-286 ◽  
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.

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

2009 ◽  
Vol 100 (6) ◽  
pp. 863-866
Author(s):  
Petr Homola ◽  
Margarita Slámovᆠ◽  
Peter Sláma ◽  
Miroslav Cieslar ◽  
Miroslav Karlík
Keyword(s):  
Accumulative Roll Bonding ◽  
Roll Bonding ◽  
Ultrafine Grained ◽  
Twin Roll Cast ◽  
Twin Roll

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

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.

Accumulative Roll Bonding of AA8006, AA8011 and AA5754 Sheets

2006 ◽  
Vol 519-521 ◽  
pp. 1227-1232 ◽  
Author(s):  
Margarita Slámová ◽  
Petr Homola ◽  
P. Sláma ◽  
Miroslav Karlík ◽  
Miroslav Cieslar ◽  
...  
Keyword(s):  
Accumulative Roll Bonding ◽  
Aluminium Alloys ◽  
Fine Particles ◽  
Industrial Practice ◽  
Roll Bonding ◽  
Roll Casting ◽  
Transmission Electron ◽  
Ultrafine Grained ◽  
Aluminium Sheets ◽  
Twin Roll

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.

Microstructural and Mechanical Characterization of ARB AZ31

2013 ◽  
Vol 765 ◽  
pp. 403-407 ◽  
Author(s):  
Friederike Schwarz ◽  
Katja Lange ◽  
Lutz Krüger ◽  
Rudolf Kawalla ◽  
Stephan Reichelt
Keyword(s):  
Grain Size ◽  
Mechanical Characteristics ◽  
Mechanical Characterization ◽  
Basal Texture ◽  
Electron Backscattered Diffraction ◽  
Roll Bonding ◽  
Average Grain Size ◽  
Twin Roll Cast ◽  
Twin Roll

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.

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