Ultra Grain Refinement of Low C Steels by Accumulative Roll Bonding

2006 ◽  
Vol 503-504 ◽  
pp. 311-316 ◽  
Author(s):  
I. Salvatori
Keyword(s):  
Accumulative Roll Bonding ◽  
Orientation Imaging Microscopy ◽  
Low Carbon Steel ◽  
Small Samples ◽  
Low Carbon ◽  
High Angle ◽  
Misorientation Distribution ◽  
Roll Bonding ◽  
Orientation Imaging ◽  
Annealing Conditions

Refinement of grain size is one of the biggest challenges to produce steels with improved combination of strength and toughness. Ultrafine structures are being produced world-wide on various materials, including low carbon steel, using different types of processes. However, the majority of these processes also exhibit severe limitations because they are generally restricted to small samples and are difficult to be implemented on an industrial scale. A promising technique for industrial implementation is the Accumulative Roll Bonding (ARB), a process able to supply large samples, even in the laboratory scale. In this paper, warm intense straining (ε = 4) by ARB was applied to a plain low-C steel in order to develop ultrafine grains, aiming at sizes around 1-2 μm, suitable to maintain an adequate combination of strength and ductility. The effect of annealing conditions on the evolution of the work-hardened microstructure and the bonding behaviour after each pass were investigated. Orientation Imaging Microscopy was used to investigate the microstructure and give a quantitative assessment of high angle and low angle boundaries. It is showed that the frequency of high angle grain boundaries increases with the strain but the misorientation distribution remained far from that typical of a recrystallised material.

THE EFFECTS OF ACCUMULATIVE ROLL BONDING PROCESS ON MICROSTRUCTURE AND MECHANICAL PROPERTIES OF IF STEEL

2008 ◽  
Vol 22 (18n19) ◽  
pp. 2866-2873 ◽  
Author(s):  
SAEED TAMIMI ◽  
MOSTAFA KETABCHI ◽  
NADER PARVIN
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Accumulative Roll Bonding ◽  
Low Carbon Steel ◽  
Rolling Process ◽  
Low Carbon ◽  
Roll Bonding ◽  
Rolling Pass ◽  
Steel Strips ◽  
Wire Brushing

This work aims to investigate whether accumulative roll bonding (ARB) is an effective grain refinement technique for ultra-low-carbon steel strips containing 0.004% C. For this purpose, a number of ARB processes were performed at 500 °C, with 50% reduction in area of each rolling pass. It was found that both the ultimate grain size achieved, as well as the degree of bonding, depend on number of rolling pass and reduction of area as a whole. The mean grain size was obtained using AFM was about 130nm. The mechanical properties after rolling and cooling were obtained. Also, the fracture surfaces were studied by Scanning Electron Microscopy (SEM). It was concluded that metal's tensile strengths increased by 334% while the ductility dropped from a prerolled value of 50.5% to 2.6%. Effect of wire brushing on samples observed too. It increased on the wire brushed sheet for 7 HV. The rolling process was stopped when cracking of the edges became pronounced.

Lamellar Subdivision during Accumulative Roll Bonding of a Titanium Interstitial Free Steel

2005 ◽  
Vol 495-497 ◽  
pp. 351-356 ◽  
Author(s):  
Ana Carmen C. Reis ◽  
Leo Kestens ◽  
Yvan Houbaert
Keyword(s):  
Shear Strain ◽  
Accumulative Roll Bonding ◽  
Rolling Direction ◽  
Orientation Imaging Microscopy ◽  
Lamellar Microstructure ◽  
Composite Sample ◽  
Interstitial Free ◽  
High Angle ◽  
Roll Bonding ◽  
Interstitial Free Steel

Titanium alloyed interstitial free steel was processed by means of accumulative roll bonding (ARB) in order to obtain an ultrafine grained structure. Ten consecutive rolling passes were applied at 480°C with a nominal reduction of 50% per pass and an intermediate annealing treatment of 5 min. at 500°C. A total true strain was obtained of evM = 8.0 which corresponds to an accumulated reduction of 99.9%. Orientation imaging microscopy was used to evaluate textures and microstructures. A pronounced lamellar structure was observed until the 5th pass with an incidence of high angle grain boundaries predominantly parallel to the rolling direction. After the 6th pass (evM = 4.8) an increased fragmentation perpendicular to the rolling direction starts to develop in spite of the lamellar microstructure with an average spacing of approximately 1 µm. From the 7th pass onwards (evM ≥ 5.6) a random high angle grain boundary distribution develops which results in a more equi-axed ultrafine microstructure after the 9th pass (evM = 7.2) with an average grain width of 200 nm. As the rolling is carried out without lubrication, the surface areas display a slightly more fragmented structure than the midlayer sections and typical shear texture components are present in these surface zones (<110>//ND and <211>//ND fibre). Although the sheets are stacked upon each other after each subsequent pass, the shear strain microstructural and textural features are rapidly decomposed in the midlayer in each subsequent rolling pass which is clearly revealed by the cross sectional orientation scan on the composite sample. Hence it cannot be concluded that the surface shear strain significantly contributes to the grain fragmentation in the bulk volume of the composite sample.

Texture Control in Steel and Aluminium Alloys by Rolling and Recrystallization in Non-Conventional Sheet Manufacturing

2012 ◽  
Vol 715-716 ◽  
pp. 89-95 ◽  
Author(s):  
Leo Kestens ◽  
Jurij J. Sidor ◽  
Roumen H. Petrov ◽  
Tuan Nguyen Minh
Keyword(s):  
Aluminium Alloys ◽  
Degrees Of Freedom ◽  
Recrystallization Texture ◽  
Low Carbon Steel ◽  
Low Carbon ◽  
Asymmetric Rolling ◽  
Recovery Processes ◽  
Annealing Texture ◽  
Annealing Conditions ◽  
Flat Rolling

The sheet manufacturing process, which involves various solid-state transformations such as phase transformations, plastic deformation and thermally activated recovery processes, determines the texture of steel and aluminium sheet. The conventional process of flat rolling and annealing only offers limited degrees of freedom to modify the texture of the final product. After annealing a {111} recrystallization fibre in BCC alloys and a cube dominated recrystallization texture in FCC metals is commonly obtained. Many applications, however, require other texture components than the ones achievable by conventional processing. In the present paper it is shown that by asymmetric rolling of a Si-alloyed ultra-low carbon steel a texture can be obtained with increased intensity on the {001} fibre, which is of interest for magnetic applications. Also in aluminium alloys the strong cube annealing texture can be drastically modified by the process of asymmetric rolling. It is argued that by observing the proper rolling and annealing conditions a recrystallization texture with improved normal and planar anisotropy of the mechanical properties may be produced.

Martensitic Transformation from Ultrafine Grained Austenite Fabricated by ARB in Fe-24Ni-0.3C

2010 ◽  
Vol 667-669 ◽  
pp. 361-366 ◽  
Author(s):  
Hamidreza Jafarian ◽  
Ehsan Borhani ◽  
Akinobu Shibata ◽  
Daisuke Terada ◽  
Nobuhiro Tsuji
Keyword(s):  
Martensitic Transformation ◽  
Accumulative Roll Bonding ◽  
Martensite Transformation ◽  
Early Stage ◽  
Crystallographic Analysis ◽  
High Angle ◽  
Metastable Austenite ◽  
Roll Bonding ◽  
Nucleation Sites ◽  
Ultrafine Grained

In this paper, martensitic transformation from ultrafine grained (UFG) austenite fabricated by accumulative roll bonding (ARB) process in a metastable austenite alloy was studied. Microstructural observations and crystallographic analysis were carried out by FE-SEM/EBSD. The results showed that elongated UFG austenite having 200-300 nm in thickness surrounded by high angle boundaries was obtained after 6 cycles of the ARB process. The martensite transformed from the UFG austenite showed characteristic morphology and texture. The martensite transformation starting (Ms) temperature increased after 1 cycle ARB, which is related to increasing amount of nucleation sites, such as low angle boundaries, introduced during early stage of ARB process. In contrast, by increasing the ARB cycles, Ms temperature decreased. Decreasing the Ms temperature could be correlated to strengthening of austenite by the ARB process.

scholarly journals Randomly oriented twin domains in electrodeposited silver dendrites

2015 ◽  
Vol 80 (1) ◽  
pp. 107-113 ◽  
Author(s):  
Evica Ivanovic ◽  
Nebojsa Nikolic ◽  
Velimir Radmilovic
Keyword(s):  
Electron Microscopy ◽  
Orientation Imaging Microscopy ◽  
Dark Field ◽  
High Angle ◽  
Orientation Imaging ◽  
Transmission Electron ◽  
Annular Dark Field ◽  
Silver Dendrites ◽  
Z Contrast ◽  
Scanning Electron

Silver dendrites were prepared by electrochemical deposition. The structures of Ag dendrites, the type of twins and their distribution were investigated by scanning electron microscopy (SEM), Z-contrast high angle annular dark field transmission electron microscopy (HAADF), and crystallografically sensitive orientation imaging microscopy (OIM). The results revealed that silver dendrites are characterized by the presence of randomly distributed 180? rotational twin domains. The broad surface of dendrites was of the {111} type. Growth directions of the main dendrite stem and all branches were of <112> type.

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