Papers by Keyword: Deformation Band

Abstract: Formation of thin macrofractures and high porosity bands parallel to the compression axis in the unconsolidated sedimentary rocks is treated on the basis of unified approach by considering migration of microdefects (pores) with respect to particles of the medium. The migration of pores is driven by a common cause, namely, a trend of a system to lower its total energy. The mechanism of how discontinuities develop along the maximum compressive stress T_max is discussed and quantitatively investigated. A single pore splits into two separate holes which move away along the T_max axis. The trace left by moving hole is interpreted as a macro-discontinuity. Multiple pores migrate so that they form a system of chains extending along the T_max axis. We associate these chains with observed high porosity bands.

Abstract: Cold-rolled micro-texture of polycrystalline 3%Si-Fe was investigated using high-resolution Electron BackScattering Patterns (EBSP) method. There were deformation bands near grain boundaries. The orientation relationship between the deformation bands and the surrounding deformed grains is explained by the orientation rotation around a <211> axis. The activated slip to generate these deformation bands is estimated from the <211> rotation. The S-value, which is a geometrical index of slip operation against applied stress, of this slip system was not maximum value of all, but it had a common slip plane with an adjacent grain. A hypothesis that the slip system having a common slip plane with an adjacent grain is activated was proposed from the present results.

Abstract: The paper surveys various types of dislocation substructure that are created by plastic deformation in metals. Special reference is made to those substructures that accommodate sharp misorientations as these are of fundamental importance to the nucleation of recrystallisation. Several different mechanisms can give rise to high misorientations; these are discussed in terms of the factors that control them and their relationships to orientation and texture. Different mechanisms for nucleation of recrystallisation may occur depending on the type of substructure, allowing some practical control over the final recrystallised texture.

Abstract: The microstructure and texture development in an extra low carbon steel during warm rolling (~ 80%) in a single pass at four different temperatures and at two different cooling conditions were studied. The g fibre texture develops at lower warm rolling temperatures (500 °C and 600 °C) and a very weak a fibre develops at higher rolling temperatures (700 °C and 800 °C). Very little or no difference in microstructure and texture development was observed under two cooling conditions at four rolling temperatures. No significant effect of cooling rates could be found at higher temperatures of rolling due to very fast static recrystallisation after rolling which also caused the weakening of texture. On the other hand deformation bands produced at low temperatures rolling helped in forming strong g fibre textures.

Abstract: IF steel was homogeneously cold rolled between 30-95% reduction in thickness. The global cold rolling textures showed a gradual strengthening of both stable α and γ components with increasing reduction until ~80% after which γ remained effectively unchanged but α components intensified until 95% reduction of thickness. Deformation Banded (DB) and also fragmented microstructures were found exclusively in γ grains up until about 85% reduction after which DB was unexpectedly detected in α grains, becoming significant after 95% reduction. This is in sharp contrast with the rather undifferentiated microstructures found in α grains at low to medium levels of deformation. At lower reductions the annealing texture was a weak α, but the γ component increased with rolling strain and became dominant at ~80% rolling deformation. A peak type γ recrystallisation texture with orientations ranging from {554}<225> to {111}<123> was found in the 95% rolled sample. In addition to this a {411}<148> component began to intensify, reading 5R at 95% reduction. Microstructural analysis showed that DB provided the lattice curvature for nucleation in the α fibre.