A novel cryogenic rolling method for commercially pure titanium sheets featuring high strength and ductility

Commercially pure titanium (CP Ti) has a low yield strength (YS); consequently, its utilization is limited to industrial applications that do not require high load-bearing capabilities. Cryogenic deformation has been regarded as an effective method for strengthening CP Ti. However, this method increases production costs and degrades ductility, thereby hindering the commercialization of cryogenic deformation for industrial production. In this study, we devised a two-temperature rolling method for CP Ti by combining room-temperature rolling (RTR) and cryogenic-temperature rolling (CTR), which can induce significant material strengthening while reducing the number of rolling passes required at cryogenic temperature. The RTR and CTR sequence substantially affected the strengthening degree. Employing CTR for only a part of the total area reduction (AR) induced considerable strengthening comparable to that obtained by employing it for the entire AR. Furthermore, the two-temperature rolling process did not appreciably degrade the ductility, despite inducing considerable strengthening, leading to an excellent strength-ductility combination. We identified microstructural factors for the high strength and ductility in the processed CP Ti. The devised rolling method is highly cost-effective, as it can reduce the proportion of cryogenic-temperature treatment in the whole rolling process; thus, this methodology will contribute considerably to the commercialization of CTR for industrial applications. (C) 2022 Published by Elsevier B.V.