Microstructural Evolution and Mechanical Properties of Ultrafine‐Grained Ti Fabricated by Cryorolling and Subsequent Annealing

Abstract

showed that the strength and microhardness of UFG Ti follow the conventional Hall-Petch relationship. [10] Several severe plastic deformation (SPD) techniques have been used to fabricate UFG samples, including Ti, such as highpressure torsion (HPT), [11-13] multidirectional forging, [14] friction stir welding, [15] equal-channel angular pressing (ECAP), [5,16,17] and special rolling technology. [18,19] It was reported that the strength of UFG Ti processed by HPT reached %1200 MPa [11] and there was a strength of %930 MPa in UFG Ti fabricated by multiforging and subsequent rolling. [14] There is a report that the mechanical properties and corrosion resistance of CP Ti after continuous ECAP plus short-duration annealing was comparable with the as-received sheets [20] and UFG Ti prepared by ECAP þ rolling had a higher strength than Ti-6Al-4V alloys. [21] Recently, a shear drawing technique was developed to fabricate UFG Ti bars and the results showed that the strength was improved to %590 MPa compared with %470 MPa in conventional drawing. [22] Deformation at cryogenic temperature may further refine the grain size compared with deformation at room temperature (RT). Aluminum alloys [23-25] and copper alloys [26-28] showed high

Grain Growth Mechanism of Lamellar-Structure High-Purity Nickel via Cold Rolling and Cryorolling during Annealing

“…Low-angle grain boundaries of LG are normally formed through dislocation multiplication and interaction during plastic straining [ 3 ]. Various severe plastic deformation techniques to produce LG material have been developed, such as surface mechanical grinding treatment [ 4 , 5 ], cryorolling [ 6 , 7 ], cross rolling [ 8 ], and other special rolling techniques [ 9 , 10 ]. The study on the grain growth mechanism of LG materials prepared by different processes with annealing can support further understanding of the thermal stability of LG materials.…”

“…They reported a novel mechanism via coarsening of the initial structure of nanolaminates with low angle boundaries called local faceting [ 14 ]. Cryorolling is a special rolling technique widely used to prepare LG materials [ 6 , 7 , 15 ]. LG aluminum alloy with high strength and high ductility can be obtained by cryorolling with proper reduction and a subsequent annealing process [ 16 ].…”