Plane Strain Compression of Nb-10Hf-1Ti alloy: Effect on Microstructure and Micro-Texture

Abstract

The development of microstructure in the course of warm deformation of niobium-10 hafnium-1 titanium (wt%) alloy (C103) was studied by plane strain compression (PSC) testing in the range of 500–650 °C and two strain rates (ἑ) 0.01 and 1 s−1 which are commercially being practiced for rolling of the alloys. A total of 75% reduction in thickness was imparted to the samples during the warm deformation. The purpose of the study was to establish the warm rolling process parameters (ἑ and T) useful in the optimization of thermomechanical processing schedules to realize thin sheets of this difficult to process refractory material. Weak softening was noticed at temperatures of 600 °C (~ 0.35Tm) and above in the stress–strain plots. Partial dynamic recrystallisation was observed at the regions where maximum strain was observed in the sample during deformation at high temperatures as evidenced by electron backscatter diffraction (EBSD). Samples deformed in the temperature range of 500 °C to 600 °C and at ἑ of 1 s−1 showed dynamic recovery. High angle grain boundary fraction is higher for the sample deformed at a temperature of 650 °C and ἑ of 0.01 s−1 compared to the sample deformed at a ἑ of 1 s−1. Based on detailed microstructural observations, it was concluded that C103 alloy can be warm rolled at a temperature of 650 °C and ἑ of 0.01 s−1 to obtain localized dynamically recrystallized grain structure in the material and it is expected that a dynamic recrytallization will further advance with increase in reduction during deformation.