Authors: Su Kwon Nam, In Soo Kim, Dong Nyung Lee
Abstract: The average plastic strain ratio (the R-value) and the anisotropy parameter |ΔR| calculated from the measured texture of AA1050 Al alloy sheet treated by the heavy asymmetric rolling by 84% reduction in thickness and subsequent annealing for 1 h at 500 °C, followed by light rolling by 10% or 20% reduction in thickness and the subsequent annealing for 1 h at 500 °C increased by 1.52 times that of the non-processed specimen and reduced to 1/12 times that of the non-processed specimen, respectively.
203
Authors: Liang Chen, Jian Guo Tang, Sheng Dan Liu, Xin Ming Zhang, Xiang Li, Bin Chen, Yun Lai Deng
Abstract: The evolution of through-thickness strain gradients during snake rolling (SR), which introduces an horizontal offset between upper and lower rolls, of Al-Mg-Si-Cu sheets was investigated with the inscribed lines in side including rolling and normal direction of sheets. The complete pole figures were used to investigate the influence of such rolling on texture evolution. The results revealed that the SR rolled sheet developed a continuous through-thickness shear strain gradients and shear textures. The surface in contact with the slower roll (the lower roll) developed the largest shear strain and the strongest shear texture. While for the conventional symmetric rolling (CR), the sheet developed a small shear strain gradient which is symmetrical about the centerline of the sheet with nearly negligible shear strain and texture at the center of the sheet.
79
Authors: Yoshimasa Takayama, Mei Qin Shi, Yoshihiro Ougiya, Kenta Nonaka, Hideo Watanabe
Abstract: Titanium and aluminum sheets were directionally strained by friction roll surface processing (FRSP). Severe shear strain was imposed into the surface layer and strain gradient was formed through the thickness of the sheet. The microstructure and texture in as-strained state were investigated by optical microscopy and X-ray diffraction technique. Ultra-fine grains in the surface layer of the titanium sheet were found to have a sharp texture with a preferred orientation strongly related to the FRSP direction. The evolution of microstructure and crystallographic texture of FRSPed samples during annealing were studied by electron back-scattered diffraction (EBSD) technique. Obvious preferred orientations of shear straining were obtained in the surface layer of both materials as a result from FRSP and subsequent annealing.
457
Authors: Ganesh Niranjan, Chakkingal Uday
Abstract: There is increasing interest in using Al alloy sheets for auto body applications. However Al alloys exhibit poor drawability as indicated by low values of the normal anisotropy, rm. Techniques for improving the value of rm rely on developing a favourable shear texture in the sheet. In this study, Al alloy AA 6061 sheets of dimensions 225 mm x 200 mm and 1 mm thick were subjected to severe plastic deformation by repeated groove pressing using a set of grooved and flat dies alternatively. The orientation of the grooves with respect to the rolling direction was also varied. Microstructure characterization and mechanical property measurements were carried out. X- ray diffraction scans were carried out to measure the relative intensities of the (111) and (200) peaks. The r values was measured as per ASTM standard E 517 on strip specimens cut at 0°, 45° and 90° to the rolling direction and the normal anisotropy value (rm) and planar anisotropy value (Δr) values were determined. The limiting drawing ratio (LDR) was determined using the Swift cupping test techniques. It was observed that the rm values increased from 0.72 in the as received condition to a maximum of 0.94 and the LDR increased from 1.93 to 2.06 when the groove pressing was carried out with grooves at to 45° the rolling direction. The improvement in rm values can be correlated to the texture developing in the sheet as a result of severe plastic deformation.
1911
Authors: Tomoko Shimamura, Tetsuo Sakai, Hiroshi Utsunomiya, S. Kaneko
Abstract: It is known that well developed <111>//ND texture increases Lankford value (r-value) of
not only bcc metals but also fcc metals and alloys. However, <111>//ND texture cannot be formed
in fcc metals by conventional rolling and annealing processes. The <111>//ND orientation is one of
the major components of shear texture. Accordingly, this orientation develops in aluminum sheet
when shear deformation is introduced.
Al-Mg-Si alloy 6016 sheet was processed by two-pass differential speed rolling at room
temperature under a high friction conditions. The rolling direction of the second pass was so
selected that the direction of shear deformation introduced in the second pass was either similar
(unidirectional shear rolling) to or opposite (reverse shear rolling) to that in the first pass. The roll
speed ratio was 2.0. Large shear strain was successfully introduced through the thickness uniformly
by the differential speed rolling. The shear texture with major components of {001}<110> and
{111}<110> were developed throughout the thickness. Though large reduction in thickness of 75%
was applied to the sheets by the rolling, conventional rolling texture such as {112}<111> or
{123}<643> orientation was not detected in any part of the thickness. By solution treatment after
the rolling, intensity of shear texture weakened and grain size decreased. It has been found that
r-value is improved by the differential speed rolling subsequently followed by solution treatment.
1443
Authors: Kee Joo Kim, Joo Sung Kim, Cheol Woong Kim, Il Seon Sohn, Jin Yi Lee, Joong Bae Kim
Abstract: To fabricate the aluminum alloys with good drawability, the textures evolution of the 3003
aluminum alloy sheets after rolling and subsequent annealing was studied. The measurement of the
deformation textures was carried out for the sheets in which were cold rolled with high reduction ratio
by using the symmetric roll. In addition, the change of the recrystallization texture was investigated
after heat-treatments of the rolled sheets with various heat treatment conditions. Rolling without
lubrication and subsequent annealing led to the formation of favorable rot-CND {001}<110> and
γ-fiber ND//<111> textures in 3003 aluminum alloy sheets. From the results, the γ-fiber ND//<111>
component well evolved during rolling at high reduction ratio (reduction over 90%, l/d parameter
over 6.0). Among shear deformation textures, the γ-fiber ND//<111> was not rotated during
recrystallization (350°C) in special condition.
579
Authors: Moo Young Huh, Hyung Gu Kang, C.K. Kang
Abstract: Asymmetrical rolling was performed by rolling AA 1050 sheets with different velocities of
upper and lower rolls. In order to study the effect of roll gap geometry on the evolution of strain states
and textures during asymmetrical rolling, the reduction per rolling pass was varied. After
asymmetrical rolling, the outer thickness layers depicted shear textures and the center thickness layers
displayed a random texture. With decreasing reduction per an asymmetrical rolling pass, the thickness
layers depicting shear textures increases. The strain states associated with asymmetrical rolling were
investigated by simulations with the finite element method (FEM).
417
Authors: Moo Young Huh, J.K. Kim, Jael Chul Lee, Han Gil Suk
Abstract: This work focuses on the strain states of the mid AA 3003 strip sandwiched in between
either AA 3003 sheets or STS 430 sheets. For that purpose, the strain states at various
through-thickness layers were analyzed by measurements of crystallographic texture and by
simulations with the finite element method (FEM). During sandwich rolling, the material property of
outer sheets of sandwich samples played an important role in the evolution of the strain states and the
corresponding texture formation. In the mid AA 3003 sheets, rolling with the harder outer sheets gave
rise to pronounced through-thickness texture gradients, whereas fairly uniform strain states prevailed
during rolling with the outer sheets of the same AA 3003.
320
Authors: Kee Joo Kim, Joo Sung Kim
Abstract: To fabricate the aluminum alloys with good drawability, the textures evolution of the
AA5182 sheets after rolling and subsequent annealing was studied. The measurement of the
deformation textures was carried out for the sheets with high reduction ratio and the change of the
recrystallization texture was investigated after heat-treatments of the rolled sheets. Rolling without
lubrication and subsequent annealing led to the formation of favorable rot-CND {001}<110> and
γ-fiber ND//<111> textures in AA5182 sheets. From the results, the γ-fiber ND//<111> component
well evolved during rolling at high reduction ratio. Among shear deformation textures, the γ-fiber
ND//<111> was not rotated in holding time until 7,200 seconds at 350. The Monte-Carlo technique
was used and could be representatively simulated textures evolution during recrystallization.
1421
Authors: Soo Ho Park, Hyung Gu Kang, Yong Deuk Lee, Jae Chul Lee, Moo Young Huh
Abstract: In order to investigate the effect of the reduction degree per rolling pass on the evolution of recrystallization textures and microstructures, the hot band of 17.5 Cr-1.1 Mo ferritic stainless steel sheets were cold rolled with lubrication according to two processing routes, by which different reduction degrees per pass were introduced. Rolling with a large number of passes led to the formation of fairly homogeneous rolling textures at all through-thickness positions. In contrast, cold
rolling with large draughts resulted in pronounced texture gradients along the thickness direction. After recrystallization annealing, the texture maximum was obtained at {334}<483> in all samples regardless of the rolling routes and thickness layers. During subsequent annealing, recrystallization was observed to be faster in those grains with {111} orientations, while it was retarded in
grains having orientations close to {001}<110>.
363