A study on the formation mechanisms of the cube recrystallization texture in cold rolled Fe–36%Ni alloys

Abstract

The formation of sharp cube recrystallization texture after high cold rolling reductions in Fe-36%Ni has been studied by means of X-ray texture measurements and extensive transmission electron microscopy (TEM) observations, including orientation measurements even in highly deformed materials. In contrast to Cu and Al, this material shows only little recovery during cold deformation; therefore, the deformation structure can be studied in detail. After high cold rolling the cube grains present at the hot rolled state show the formation of cells and the development of a large orientation gradient inside cube bands. During recrystallization nucleation of cube grains proceeds at a high rate inside these structures. For low deformations cube grain nucleation seems to be inhibited due to the insufficient orientation gradient across the cells. Regions of other orientations show a much lower nucleation rate owing to their inappropriate microstructure. Thus, other recrystallization textures only develop if the cube nucleation is inhibited.

Supercube grains leading to a strong cube texture and a broad grain size distribution after recrystallization

“…Moreover, the relative frequency of cube grains is almost constant during recrystallization, which means that cube grains do not nucleate earlier than noncube grains. It was suggested previously that the deformed matrix of cube orientation recovered faster, which lead to earlier nucleation of cube grains [3,33]. However, effects of this are not evident in the present sample.…”

“…A small amount of cube texture (~2% volume fraction) is observed, which has been seen in cold-rolled copper [4] and other metals [33,34]. The cube oriented regions are usually observed as thin bands (see Figure 2a).…”

Deformation mechanism of cryorolled Fe-36%Ni strip steel

“…For Fe-36%Ni steel with the SFE of 122 mJ m −2 [13], dislocation slip is the common deformation mechanism informed from the previous studies [3], and the information about mechanical twinning is limited. It is well understood that twinning is the main deformation mechanism in materials with low SFE, such as Cu-Al alloy, twinninginduced plasticity (TWIP) steels [14].…”

“…So far, the plastic deformation behaviour, formation mechanism of the cube texture during cold rolling and work hardening rate of Fe-36%Ni steel have been well understood [2][3][4]. The microstructure and texture studies have been carried out by traditional cold rolling, asymmetrical rolling and accumulative roll bonding.…”

“…The microstructure and texture studies have been carried out by traditional cold rolling, asymmetrical rolling and accumulative roll bonding. Zaefferer et al [3] found that Fe-36%Ni steel shows little recovery during cold rolling, and the cube recrystallization texture is observed after the high cold rolling due to cube nuclei develop significantly quicker than other orientations. By 83% thickness reduction asymmetrical rolling, the main deformed texture of Fe-36Ni% steel is copper texture with a little rotation around the transverse direction axis, which revealed the formation of shear texture during asymmetrical rolling [5].…”