Modeling and optimization of equivalent plastic strain in equal-channel angular rolling using response surface methodology

Abstract

The mechanical properties of metallic strips can be improved by producing an ultra-fine-grained microstructure. The equal-channel angular rolling process is a severe plastic deformation technique suitable for such a purpose. In this article, the effect of the equal-channel angular rolling parameters on the equivalent plastic strain is investigated and their optimum values are reported. The analysis is focused on the following parameters: thickness ratio (K), die channel angle (u), die outer corner angle (c), fillet radius (r), friction coefficient between strip and rolls (m), and friction factor between strip and die (m). Using a combination of the finite element modeling and the response surface methodology with central composite design, a simple and efficient quadratic model is developed to predict the equivalent plastic strain dependence on the equal-channel angular rolling process parameters. The analysis of variance is applied to assess the validity of the model and find the significant parameters. The results show that the die channel angle is the most significant parameter, while the friction coefficient between strip and rolls has no considerable effect on equivalent plastic strain. Moreover, the following optimum values of the parameters are obtained: K = 0.96, u= 90.10°, c= 21.21°, r = 2.31 mm, m= 0.20, and m = 0.19. An increase of about 14.86% in the equivalent plastic strain can be achieved by adopting these values for the process parameters.

Numerical and experimental studies on deformation behavior of 5083 aluminum alloy strips in equal channel angular rolling

“…In this simulation, the strip is divided into 8900 nodes and 8001 elements. Therefore, in Chari et al, 24 the validation of the FEM simulation has been done and confirmed by comparing of the inclination angle with an analytical approach. Moreover, using some analytical equations, the obtained strain from the simulation was compared with the analytical relations.…”

“…Results showed that shear deformation, stress homogeneity and strain distribution can be improved due to the friction between the die walls and the workpiece. Chari et al 24 utilized both the response surface methodology and the finite element method (FEM) to predict the effect of process parameters on equivalent plastic strain in ECAR. The results indicated that the friction coefficient on the interface of the rolls and strip has no significant effect on effective strain, while the die channel angle is the most considerable parameter.…”

Experimental and numerical study on the ECARed magnesium AZ31 alloy

“…To assess the friction coefficient effect on the imposed strain (for lubrication condition) three values of 0.14, 0.17 and 0.21 has been considered [5,19]. These effects are shown in Figure 10.…”

“…So far, a a Corresponding author: a asgari@mecheng.iust.ac.ir few researchers have been reported on the ECAR process. For example, Chari et al [5] presented modeling and optimization of equivalent plastic strain in equal-channel angular rolling using response surface approach. Chung et al [6] introduced an analysis of accumulated deformation in the equal channel angular rolling process.…”

Modeling of equal channel forward extrusion force using response surface approach

“…So far, very few studies have been presented an assessment of significant parameters using statistical method on the SPD processes and particularly ECFE process. For example, Chari et al 16 presented modeling and optimization of equivalent strain in equal channel angular rolling (ECAR) using RSM. Mohammed Iqbal and Kumar 17 presented a study about application of RSM in twist extrusion process parameters of Al-6082.…”