bcc orientation

1. ORIENTATION REPRESENTATION IN BCC ALLOYS
[IRON AND STEEL]
GERUGANTI SUDHAKAR
PHD(MATERIAL ENGINEERING)
20ETPM09

2. O

6. Texture study in materials science is in essence a quanti- tative
statistical study of crystallographic phenomena that contribute
to the shaping of microstructure. It filters out the relevant
crystallographic orientations that appear in solid-state
transformation processes, occurring during making and using of
materials. Hence, detailed study of the textures, as made
possible by evermore sophisticated experimental instruments
and more powerful numerical tools, provides a major gateway
to better understanding the complex mechanisms involved in
phase transform- ations, plastic deformation and thermally
activated recov- ery. The present paper has presented a minute
review, by no means exhaustive, of acquired achievements over
the past decades and current open issues in the texture
literature.

7. The study of crystallographic texture is important for three
distinct reasons:
(i) a multi- tude of material properties, and most noticeably
the ani- sotropy of these properties are dependent on the
crystallographic texture (essentially, each property that is
orientation dependent in a single crystal will be texture
dependent in the polycrystalline assembly);
(ii) the appearance of a crystallographic texture tells something
about the physical mechanisms that are involved in the
formation of the microstructure. Theories on solid-state
transformation processes occurring during metals proces- sing
such as phase transformation, plastic deformation or
recrystallisation are incomplete without fully understand- ing
the crystallographic implications of such theories, which also
may entail consequences for texture formation.
(iii) Since the late 1980s, knowledge on the crystallo- graphic
aspects of the microstructure has given rise to the
development of orientation contrast microscopy, based on
EBSD technique (Electron Back Scatter Diffrac- tion). Nowadays
EBSD provides one of the most com- plete and detailed
metallographic imaging techniques in the resolution range
accessible to scanning electron microscopy

8. Schematic representation of lattice rotation as a conse- quence
of slip activity in a single crystal with hypothetical primitive
cubic structure: a initial situation, b crystal after unit shear and
c lattice rotation imposed by boundary con- dition of fixed
tensile axis
Schematic representation of lattice rotation as a conse-
quence of slip activity in a single crystal with hypothetical
primitive cubic structure: a initial situation, b crystal after
unit shear and c lattice rotation imposed by boundary con-
dition of fixed tensile axis