Response surface modeling and optimization of equivalent plastic strain in equal channel angular rolling

Equal channel angular rolling (ECAR) process is a severe plastic deformation technique which is performed on metallic sheets and strips. It helps to obtain the desired mechanical and physical properties through refining the grain size. In this paper, the effect of the ECAR process parameters, the thickness ratio ( k ), the die channel angle (F ), the die outer corner angle ( Y ), the fillet radius (r), the friction coefficient between strip and rolls ( μ ) and the friction factorbetween strip and die ( m) on the equivalent plastic strain (PEEQ) have been investigated. A simple and efficientquadratic model has been obtained to predict the PEEQ as the function of the ECAR parameters. The results showed that the die channel angle is the most significant parameter while the friction coefficient between the strip and the rolls has no considerable effect on the PEEQ. Furthermore, it is found that there are some interactions between the ECAR process parameters. The optimum values of the parameters which result in the maximum PEEQ, k = 0.96, F = 90.10 , Y = 21.21 , r = 2.31mm, μ = 0.20 and m = 0.19 , have been determined using finite element analysis and response surface methodology with central composite design. An improvement about 14.86% in the PEEQ was achieved by setting the optimum values for the process parameters.

کلیدواژه ها:

Equal channel angular rolling ، Severe plastic deformation ، Finite element analysis ، Response surface methodology