The investigation of springback of UFG commercially pure titanium in three-point bending test

Equal channel angular pressing (ECAP) is one of the most effective processes to produce ultra-fine grain (UFG) and nano-crystalline (NC) materials. Commercially pure titanium (CP-Ti) has a significant potential to be used as a biomedical and implant material because it shows excellent biocompatibility properties. This material has the low static and dynamic strengths. By applying the ECAP process, the strength of CP-Ti could be developed. The elastic recovery during unloading or spring-back phenomenon is one of the most sensitive parameters in sheet and bulk metal forming processes. This phenomenon leads to some unfavorable geometrical and dimensional changes in the final products and it must be decreased. In this study CP-Ti of Grade 2 is ECAPed at the room temperature via a channel angle of 135° for 3 passes. The microstructural analysis and mechanical tests such as the tensile and three-point bending tests are all performed on the ECAPed CP-Ti. The microstructural evolution reveals that by applying the ECAP, coarse grain (CG) structure develops to UFG structure. Moreover, the results of the mechanical tests show that applying the ECAP significantly increases tensile and bending strengths of the CP-Ti. Investigation of springback in three-point bending of unECAPed/ECAPed CP-Ti is conducted by experimental and finite element simulation methods using the Abaqus software. The results of this study reveal that by applying the ECAP, spring-back values increase. Thus, to eliminate the disadvantages of springback phenomenon, this should be considered in design and manufacturing of products include bent made of ECAPed material.