194
S. S. Nayak et al.
(e.g. electrical, chemical, etc.) of the material. Complete knowledge of microstructure conveys the idea of the arrangement and orientation of grains in a material, their
size and shape, phases present, grain boundaries, dislocations, etc. The components
of the microstructure are large groups of atomic arrangements which mean the position of all atoms present in the unit cell. It is described by the fractional coordinate of
the atoms and the type of lattice. Single-crystal/grain consists of no grain boundary,
and its atomic structure repeats periodically across its whole volume. But most of
the materials are polycrystalline in nature. This means the material is made up of
more than one grain or crystal, and the orientation of each grain (texture) differs
from its neighbouring one. In a real polycrystalline material, some of the individual
grains or crystals have a particular kind of orientation, whereas others do have a
set of different orientations. Here, the polycrystalline material is called a “textured”
one. The texture is known as the preferred orientation of grains. Different textures
form anisotropy, which means material properties, are different in different crystallographic planes and directions. This anisotropic property may or may not be desirable
from a realistic viewpoint. A careful control of texture will enable improving many
properties such as yield strength, elastic constants, magnetic susceptibility, electrical conductivity, piezoelectricity, wave propagation and refraction of light. This
will enhance the performance of a material for various applications. An example can
drag readers’ attention towards the importance of reading this chapter and understand
the importance of microstructure and texture.
Nowadays, in the automotive industry, the main aim is to increase the application
of lightweight materials so as to decrease the fuel consumption and the greenhouse
gas emissions [1]. For example, magnesium is a widely used material among all light
weight automotive materials, but it has poor elongation and low strength as compared
to steel and aluminium. However, by careful control of texture in magnesium, it is
possible to improve its elongation. This is possible by the application of multiaxial
forging operation on the magnesium material which leads to refinement of its grain
microstructure thereby improving its strength and elongation [2], enabling it to be
used in automotive and aerospace applications.
Texture plays an important role in rolling, forming, machining, and welding. In
the present chapter, evolution of microstructures and their preferred orientation have
been discussed in the welding. Most of the industries (i.e. mechanical construction including naval, automotive, locomotive, nuclear and aviation industries) utilize
welding to assemble the metallic materials. Welding is a manufacturing process
used to join similar or dissimilar materials permanently. At the intersection of two
metallic materials, a weld-bead is formed which joins them. It may be divided into
two broad categories, depending on whether or not the parent materials are fused for
weld-bead formation. The categories are fusion and solid-state welding processes.
In the former, both the base materials along with the filler material are fused by the
application of heat which is applied externally for the formation of the weld-bead.
In this, phase transformation occurs from solid to liquid and then again from liquid
to solid. Examples of a few fusion welding processes are: arc welding, gas welding,
resistance welding, laser and electron beam welding processes. In solid-state welding
processes, the melting of materials does not take place, rather the joining occurs in
S. S. Nayak et al.
(e.g. electrical, chemical, etc.) of the material. Complete knowledge of microstructure conveys the idea of the arrangement and orientation of grains in a material, their
size and shape, phases present, grain boundaries, dislocations, etc. The components
of the microstructure are large groups of atomic arrangements which mean the position of all atoms present in the unit cell. It is described by the fractional coordinate of
the atoms and the type of lattice. Single-crystal/grain consists of no grain boundary,
and its atomic structure repeats periodically across its whole volume. But most of
the materials are polycrystalline in nature. This means the material is made up of
more than one grain or crystal, and the orientation of each grain (texture) differs
from its neighbouring one. In a real polycrystalline material, some of the individual
grains or crystals have a particular kind of orientation, whereas others do have a
set of different orientations. Here, the polycrystalline material is called a “textured”
one. The texture is known as the preferred orientation of grains. Different textures
form anisotropy, which means material properties, are different in different crystallographic planes and directions. This anisotropic property may or may not be desirable
from a realistic viewpoint. A careful control of texture will enable improving many
properties such as yield strength, elastic constants, magnetic susceptibility, electrical conductivity, piezoelectricity, wave propagation and refraction of light. This
will enhance the performance of a material for various applications. An example can
drag readers’ attention towards the importance of reading this chapter and understand
the importance of microstructure and texture.
Nowadays, in the automotive industry, the main aim is to increase the application
of lightweight materials so as to decrease the fuel consumption and the greenhouse
gas emissions [1]. For example, magnesium is a widely used material among all light
weight automotive materials, but it has poor elongation and low strength as compared
to steel and aluminium. However, by careful control of texture in magnesium, it is
possible to improve its elongation. This is possible by the application of multiaxial
forging operation on the magnesium material which leads to refinement of its grain
microstructure thereby improving its strength and elongation [2], enabling it to be
used in automotive and aerospace applications.
Texture plays an important role in rolling, forming, machining, and welding. In
the present chapter, evolution of microstructures and their preferred orientation have
been discussed in the welding. Most of the industries (i.e. mechanical construction including naval, automotive, locomotive, nuclear and aviation industries) utilize
welding to assemble the metallic materials. Welding is a manufacturing process
used to join similar or dissimilar materials permanently. At the intersection of two
metallic materials, a weld-bead is formed which joins them. It may be divided into
two broad categories, depending on whether or not the parent materials are fused for
weld-bead formation. The categories are fusion and solid-state welding processes.
In the former, both the base materials along with the filler material are fused by the
application of heat which is applied externally for the formation of the weld-bead.
In this, phase transformation occurs from solid to liquid and then again from liquid
to solid. Examples of a few fusion welding processes are: arc welding, gas welding,
resistance welding, laser and electron beam welding processes. In solid-state welding
processes, the melting of materials does not take place, rather the joining occurs in