Constrained bending and straightening-a proposed method for severe plastic deformation of metals

The use of severe plastic deformation (SPD) technology to process ultra-fine/nano grains metals with enhanced desired properties for structural and biomedical applications have shown good results. However, SPD technology is still limited to discrete processes, small size samples with inhomogeneous strain. This paper proposes a new method for severe plastic deformation of metals known as constrained bending and straightening (CBS). The method is aimed to provide continuous production of ultra-fine/nano grains metals with improved strain homogeneity. The CBS process analytical model and its working principle are presented, a constitutive relation of feed length, bend roller diameter, effective strain and tensile strength is established. Results show that the magnitude and homogeneity of induced effective strain and tensile strength increase with the decrease of both feed length and bending roller diameter. Effective strain increased by 200% from 6mm to 2mm feed lengths. At 2mm feed length, tensile stress increased from 1223.8 MPa at 1 pass to 1302.5 MPa at 4 pass. Results from this study promise that CBS technique is potential to be adapted for continuous SPD of bulky length metal sheets with enhanced homogeneous properties.