Abstract
Near β titanium alloy Ti-55531 with an acicular starting microstructure was isothermally compressed at 750–825 °C and 10−3−1 s−1. The microstructure evolution and its influence on the flow behavior of yielding and softening were investigated. Discontinuous or continuous yielding depends on the hindrance to the dislocation motion coming from the β grain boundary or α phase. At higher temperatures, the hindrance mainly comes from the β grain boundary. Its discontinuous action, including the piling-up and subsequent loosening of dislocations at the β grain boundary, leads to discontinuous yielding. At lower temperatures, the continuous hindrance to the dislocation motion, which is exerted by the β grain boundary and acicular α, causes continuous yielding. Sequentially, the substructures in acicular α are evolved from high-density dislocations or local shear bands, which depend on the orientation relationship between β and α. Then, the β matrix edges into the acicular α along substructure boundaries. The higher strain rate decreases the deformation time to carry out the fragmentation of acicular α, while the higher temperature decreases the dislocation density due to the recovery of β, which does not benefit the substructure formation and subsequent fragmentation of acicular α. Therefore, the retardation of acicular fragmentation and the as-resulted decreased flow softening rate are observed.
Highlights
Near β titanium alloys such as Ti-55531 (Ti-5Al-5Mo-5V-3Cr-1Zr) have a good combination of strength, fracture toughness, and fatigue resistance, which are extensively used as a kind of high-performance aerospace structural material [1,2,3,4]
The stress decreased with the increase of temperature and the decrease of strain rate
At the relatively low temperature and strain rate, the continuous yielding only displayed a continuous flow softening after the peak stress
Summary
Near β titanium alloys such as Ti-55531 (Ti-5Al-5Mo-5V-3Cr-1Zr) have a good combination of strength, fracture toughness, and fatigue resistance, which are extensively used as a kind of high-performance aerospace structural material [1,2,3,4]. The resultant important phenomena include the substructure formation and sequential fragmentation in acicular α, which are closely related to the dislocation motion, especially the slip transmission at the α/β interface. During the deformation of near β Ti-alloys, the acicular α are easy to move, rotate, or bend at the action of the plastic flow of the β matrix This suggests that the orientation relationship between α and β is mutable, leading to complexity in the slip transmission at the α/β interface. The influence of this complexity on the substructure formation pattern has seldom been reported. The dislocation evolution at different orientation relationships between neighboring α and β phases, as well as its influence on the following substructure formation and fragmentation in the acicular α, were analyzed
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
