Effect of Mode of Rolling on Recrystallization Kinetics and Microstructure Evolution in Interstitial Free High Strength Steel Sheet

Abstract

The recrystallization kinetics and microstructure evolution after unidirectional and multi-step cross rolling of interstitial free high strength steel has been investigated systematically. Microhardness, electron backscattered diffraction and X-ray diffraction was used to characterize the recrystallization kinetics, microstructure and texture evolution during annealing. The obtained experimental data on recrystallization was evaluated in terms of Johnson-Mehl-Avrami-Kolmogorov (JMAK) kinetic model. The Avrami exponents varied between 1.03 at 1 073 K to 1.4 at 948 K for unidirectionally rolled sample, while for cross rolling, it varied between 2.6 at 1 073 K to 0.83 at 948 K. The recrystallization kinetics was observed to be faster for unidirectionally rolled samples. The deformed textures consisted of strong γ (ND//<111>) and α (RD//<110>) fibres in unidirectionally rolled sample, while a weak γ-fibre and strong rotated cube ({100}<110>) texture component was observed in cross rolled sample. After complete recrystallization, strong γ-fibre was observed in unidirectionally rolled sample, while strong γ and ε (TD//<110>) fibres were observed in cross rolled sample. The formation of recrystallization texture in unidirectionally rolled sample was explained by oriented nucleation. In cross rolled samples, orientation pinning and selective growth have a very strong role to play in developing the recrystallization textures.

Influence of cross-rolling on the micro-texture and biodegradation of pure iron as biodegradable material for medical implants

“…The effect of deformation mode on recrystallization behaviour of cross-rolled metal was earlier reported by Michalak and Hibbard [21]. UD rolling of pure iron leads to faster recrystallization kinetics hence a smaller recrystallized grain size than cross rolling for the same amount of deformation whereas BD rolling produces a lower dislocation density in the samples compared to UD rolling [7,29] thus lowering the driving force for primary recrystallization and resulting in a lower amount of nucleation sites causing a larger recrystallized grain size readily after 2 h of annealing. Table 3 Mean grain size and preferential orientation information of the as-received and treated samples.…”

Microstructural evolution, recovery and recrystallization kinetics of isothermally annealed ultra low carbon steel

“…They have explained the slow mechanism of initial recrystallization, which attributed to the occurrence of solute atoms in an iron lattice. Moreover, other researchers have reported the variation of 'n' values for high strength IF steel between 1.4 at 675°C and 1.03 at 800°C for unidirectional rolled samples, while 'n' varies between 0.83 at 675°C and 2.6 at 800°C for cross rolled samples [36]. The constant 'k' value decreases with, reflecting the temperature dependence for nucleation and growth rates [3].…”

“…The lower activation energy at the initial of recovery is owing to high stored energy developed through high dislocation density at the deformation. The activation energy for Ti-Nb stabilized IF steel increases to 173-312 kJ mol −1 with the effect of excess solute Ti and Nb at the iron lattice or fine carbides and nitrides are accomplished of restraining the recovery process [4,36]. Similarly, Alvarez et al reported that the activation energies of Cr-Mo pre-strained steel are 288.3 and 266.6 kJ mol −1 for 2.6 and 7 pct deformation, respectively [37].…”

“…The recovery and recrystallization kinetics are determined by isothermally annealed samples at temperature of 350, 400, 520, 550, 580 and 640°C. Several literatures have been reported for different models on the basis of mechanical and magnetic parameters [35,36]. Therefore, magnetic and mechanical softening due to decrease of coercivity and hardness are considered for recovery and recrystallization kinetics, respectively.…”

“…The values of the activation energy estimated for recrystallization (Q rex ) increases from 114-190 kJ mol −1 with recrystallization fraction increasing from 0.30 to 0.90. Khatirkar et al reported the activation energy of unidirectional cold rolled (80%) interstitial free high strength (IF-HS) steel is 216 kJ mol −1 for annealing temperatures of 675 and 800°C [36]. The activation energy of low carbon (0.025 and 0.155 wt%) plastically strained steels is explained between 276.12-287.56 kJ mol −1 [43].…”