Microstructure and texture evolution during equal channel angular extrusion of interstitial-free steel: Effects of die angle and processing route

Abstract Die angle ( Φ ) and processing route are two important factors that greatly impact microstructure and texture developments during equal channel angular extrusion (ECAE). In this study, the microstructure and texture evolution in interstitial-free steel during ECAE using a Φ = 120° die are investigated for up to four passes via three routes (A, B C and C). Finite element simulations and polycrystal modeling using the Taylor and viscoplastic self-consistent models are conducted to help understand deformation behavior and texture formation. Transmission electron microscopy results reveal remarkable microstructural differences between various observation planes for each billet. The effects of Φ and processing route are discussed by comparing the current results with those for the same material processed via the same routes but using a Φ = 90° die. The efficiency of grain refinement is found to be only mildly dependent on Φ and processing route. The textures can be completely characterized by predefined ideal fibers, regardless of processing route and pass number. With the exception of even-numbered passes in route C, textures developed after the same route and pass number, but different Φ can be approximately related by a rotation about the axis normal to the flow plane and the rotation angle is half of the Φ difference.