Investigation of dynamic flow and strength properties of Ti-6-22-22S at normal and elevated temperatures

Abstract

This paper is concerned with the material behavior of Ti-6-22-22S titanium alloy as a function of strain rate and temperature. Results of measurements of the material behavior at compressive loading under uniaxial stress conditions over a strain rate range of 10 −4 s −1 to 10 3 s −1 and under uniaxial strain conditions at shock-wave loading with a strain rate of ∼10 5 s −1 are presented. The test temperature was varied from 20°C to 620°C. The uniaxial stress compression tests revealed a rather strong strain rate sensitivity and temperature dependence of failure and flow stresses. In plate impact tests, the dynamic yield stresses at plastic deformations of 0% and 0.2% and dynamic strength (spall strength) were measured as a function of temperature. The strain-rate and the temperature dependencies of the yield stress obtained from the uniaxial stress tests and from the shock-wave experiments are in good agreement and indicate that the thermal activation mechanism of plastic deformation of the alloy is maintained at strain rates up to 10 5 s −1 at least. The relative decrease in the yield strength in the plate impact tests much exceeds the spall strength decrease. That is considered as an evidence, that the spall strength magnitude is influenced more by the contribution of the nucleation of voids rather than by the growth of voids.