Mathematical model of deformation and microstructural evolution during hot rolling of aluminium alloy 5083

Abstract

A mathematical model to predict the through thickness temperature, strain and strain rate distributions during hot rolling and the subsequent microstructure evolution was developed using the commercial nite element package ABAQUS. Microstructure evolution predictions included the amount of recrystallisation through the thickness of the sheet based on its thermomechanical history during rolling and thermal history after rolling. The equations used to predict the microstructure evolution were based on semiempirical relationships found in the literature for a 5083 aluminium alloy. Validation of the model predictions was done using comprehensive experimental measurements which were conducted using the Corus research multimill, a pilot scale experimental rolling facility, in Ijmuiden, The Netherlands. The results indicate that the through thickness temperature and strain distribution predictions for the rolling operation are reasonable. Hence, the boundary conditions used in the nite element model adequately represent the interface heat transfer and friction conditions. Microstructure predictions using the literature based equations signi cantly underestimate the amount of recrystallisation occurring in the sheet. A sensitivity analysis indicates that the recrystallisation kinetics are extremely sensitive to the tting parameters used in the microstructure equation, and that the gradient in the recrystallisation kinetics is the result of the temperature gradient experienced by the specimen during deformation.A material constant in Garafolo law B constant in Avrami equation C, a, b, c material constants in t 0 . 5 equation C p speci c heat, J K 2 1 d 0 initial grain size, mm h heat transfer coef cient, kW m 2 2 K 2 1 k thermal conductivity, W m 2 1 K 2 1 m material constant in Garafolo law n Avrami exponent P interface pressure, Pa q heat ux, W m 2 2 q . heat released owing to plastic work, W Q activation energy, J mol 2 1 r radial position through work roll, mm R universal gas constant, J mol 2 1 K 2 1 t time, s dt time increment, s T temperature,°C, K W temperature compensated time parameter, s x position along length of strip, mm X V fraction transformed, % y position through thickness of strip, mm Y(t) thickness of strip at time t, mm Z Zener -Hollomon parameter, s 2 1 a material constant in Garafolo law e strain e . strain rate, s 2 1 g ef ciency of conversion of deformationenergy to heat m coef cient of friction r density, kg m 2 3 s ow stress, MPa t shear stress, Pa

Mathematical Modeling of Multipass Hot Deformation of Aluminum Alloy AA5083—Model Development and Validation

“…Details of the model development, thermal boundary conditions, mechanical boundary conditions, and the model validation for single-pass rolling cases are described thoroughly in previously published works. [3,16,17] …”

Modeling of Structure Evolution During Hot Rolling of Aluminum Alloys in the Software Package Deform

“…is proportionality coefficient andksreflect influence of spatial factor nucleuses nd growth for 5182 alloy recrystallization according to [6], =0.693, ks=2.…”

“…Important issues, for example, are investigation of recrystallization during inter-deformation intervals and self-annealing after hot rolling. To solve them, a lot of models describing kinetics of aluminum alloy recrystallization have been created for the last 20 years [5][6][7][8]. They are mainly based on Kolmogorov-Avrami equation.…”

Editorial

“…Construction of such a mathematical model requires understanding of several inter-connected processes such as work hardening, recovery, precipitate growth and coarsening, recrystallisation and grain growth (static and dynamic) and, inevitably, numerous approximations have had to be made; this leaves the way open for others to make further refinements. [58][59][60][61] A more recent paper by Ahmed et al 62 shows that significant strides have been made on this topic of late.…”