Abstract
The microstructure evolution during solution treatment at (alpha+beta) two phase region and subsequent aging process at 620 ˚C, after compressing the specimen in beta structure to different strain (0-70%) followed by cooling to room temperature has been investigated. Deformation strain hardly affects the total volume fraction of alpha phase after the solution treatment and aging process. On the other hand, with an increase in deformation strain, the volume fraction of the primary alpha phase increased although secondary alpha phase decreased, during the aging process, scuhdecrease in secondary alpha phase volume fraction results in a decrease in the strength. The loss of coherency of alpha/beta interphase boundaries at higher deformation strain promoted by dynamic recovery increases the interfacial mobility; which results in faster growth of primary alpha, thereby decreases secondary alpha precipitation.
Highlights
Ti-17(Ti-5Al-2Sn-2Zr-4Mo-4Cr(mass%)) is a metastable beta (β) Ti-alloy primarily used in the aerospace industry for parts such as compressor and turbine discs, because of its excellent combination of tensile strength, fracture toughness and combined strength, and low cycle fatigue capabilities [1, 2]
Avoid the effect of such heterogeneity, the cylindrical sample was solutionized at 900oC, slightly above the β transus temperature for 10 min initially, to obtain homogenous β microstructure and cooled down to 800oC and compressed to 0%, 30%, 50% and 70% reduction in height, at a constant initial strain rate of 0.0033 s-1 using thermomechanical simulator Thermechmastor-Z
The a phase precipitated at the β grain boundaries is mostly in the film shape than globular (GBα), whereas in the Widmanstätten plate α (Wα) forms close to b grain boundaries and very fine in size as highlighted by the inset
Summary
Ti-17(Ti-5Al-2Sn-2Zr-4Mo-4Cr(mass%)) is a metastable beta (β) Ti-alloy primarily used in the aerospace industry for parts such as compressor and turbine discs, because of its excellent combination of tensile strength, fracture toughness and combined strength, and low cycle fatigue capabilities [1, 2]. The typical processing route followed for such titanium alloys consists of, series of hot working in β structure above or below the β transus temperature (Tβ) and followed by (alpha+beta) solution treatment and the aging process. During this processing, the precipitation of alpha (α) phase occurs, whose morphology, volume fraction, size and distribution depend upon the processing parameters, which inherently influence the properties of the Ti-17 alloy [3, 4]. Very few researches have been conducted to understand the effect of hot deformation conditions on the microstructure evolution during subsequent solution treatment and aging. The effect of deformation strain on the microstructure evolution during solution treatment and aging is investigated
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
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 call
