Deep Drawing of constrained groove pressed EDD steel sheets

Abstract

Constrained groove pressing (CGP) is a severe plastic deformation process for producing ultra-fine grained sheet metal without any change in the initial dimensions. CGP works on the principle of repetitive shear deformation of the material by alternate pressing by using asymmetrically grooved die and flat die constrained tightly by boundaries of the die. In this study, CGP, up to two passes has been performed on Extra deep drawing (EDD) steel specimens. To study the formability, the CGPed steel specimens have been deep drawn using a typical deep drawing setup and the limiting draw ratio (LDR) has been calculated. This LDR of CGPed material has been compared to the LDR of cups drawn using as-received EDD steel blanks. The formability of the CGPed material is almost the same as that of the as-received material. Apart from this, micro-hardness study of the cups has also been done on a similar comparative basis. These investigations show a slight improvement in the hardness values. It is found that by doing two passes of CGP on EDD steel, stronger cups can be produced without sacrificing much of the formability.