B. Cherukuri, R. Srinivasan, Wright State University, Dayton, OH; S. Tamirisakandala, FMW Composites, Bridgeport, WV; S. Roy, S. Suwas, Indian Institute of Science, Bangalore, India
The addition of trace amounts (~0.1wt %) of boron has been shown to significantly reduce the as-cast grain size in several common alpha, alpha+beta and near-beta alloys. This presentation will include results of a study on the effect of boron on thermomechanical processing of two metastable beta titanium alloys: Beta21S (Ti-15Mo-2.6Nb-3Al-0.2Si) and Ti-5553 (Ti-5Al-5V-5Mo-3Cr) by conducting hot compression tests at different temperatures and strain rates. Though no significant differences were observed in flow behavior between the boron-containing and boron-free alloys below the beta transus, above the beta transus flow softening was observed in boron-containing alloys, while strain hardening was observed in the boron-free alloys. Differences in the recrystallization behavior between the boron-containing and boron-free alloys were also observed above the beta transus. The presence of hard TiB particles in the boron containing alloys resulted in the formation of voids during deformation. Since the flow stress of the metallic matrix varied significantly over the deformation conditions used in this study, the nature and location of the cracks depended on strain rate, temperature and the base alloy composition. Finite element simulations were conducted to model conditions that could lead to the formation of voids during deformation.
Summary: This paper presents the results of a study on the elevated temperature thermomechanical processing two near-beta alloys, Beta21S (Ti-15Mo-2.6Nb-3Al-0.2Si) and Ti-5553 (Ti-5Al-5V-5Mo-3Cr), which have been modified with a trace addition (0.1 wt%) of boron.
