Low-carbon strip steels 17.................. !10"o"""
s ~ ,, .'"" ~ 4
~-~0.2 ~ 2
~ o S~
0 ........ _, ............ 0
0 30 ~ 60 ~ 90 ~
(001)[1 ~0] (110)[1 TO]
Odentatlon about [110]Figure 1.13 Variation of subgrain diameter (sd) and subgrain misorientation (0) with
orientation from (001) [1-i"01 to (110) [11-0]. (Dillamore et al. 3~close to the original grain boundaries are usually higher than within the grains
because the deformation must accommodate the deformation on differently orien-
tated slip systems on either side of the boundary. The deformed grain boundaries
are, therefore, preferred sites for the nucleation of recrystallized grains. 29 When
recrystallization takes place after cold rolling, the recrystallized texture is clearly
influenced by the deformation texture that is developed as well as by oriented
nucleation and selective growth effects 34 that arise from the deformation structure
itself and from other effects described below.
An example of a texture change that occurs during recrystallization, using data
for a vacuum-degassed steel, is given in Figure 1.14. This gives the intensities
along the oe and y fibre components as a function of time through the annealing
process. It is seen that overall, the y fibre components increase in intensity and
that many of the t~ fibre components decrease except those that are common to
the y fibre components. In the y fibre, the components close to (111)[ 112] clearly
develop more strongly than components close to (111)[011 ].
The percentage cold reduction has an important influence on the grain size
developed during recrystallization as well as on the texture. Increasing cold
reduction generally leads to a finer grain size, but both the grain size and the
recrystallization texture are also strongly influenced by the presence of alloying
elements in solution and by the presence of precipitates. The hot band grain
size also has an influence on the recrystallized grain size as well as its influence
on texture, as illustrated for an aluminium-killed steel in Figure 1.15. It is also
useful to note that the textures in many steels may be improved as a result of
grain growth after recrystallization is complete, but grain growth may be inhibited
by the presence of precipitates.
Many workers have shown that carbon and nitrogen in interstitial solid solution
during annealing have a detrimental effect on the texture developed during recrys-
tallization. With higher interstitial carbon contents there is a gradual decrease in
the (111) components during recrystallization, whereas with low-solute carbon,