Effect of microstructure and texture on directional dependent plastic flow behavior of refractory alloy Nb-10Hf-1Ti

Abstract

This article investigates the directional dependency of the tensile plastic flow and work-hardening behavior of a cold-rolled plus annealed sheet made of the refractory alloy Nb-10Hf-1Ti. Three tensile test directions such as 0° to the rolling direction (RD) (sample-S0), 45° to the RD (sample-S45), and 90° to RD (sample-S90) have been used in this investigation. When the tensile test is performed along 0° and 90° to RD, both the α- and γ-fibres evolve, and the overall texture intensity decrease while testing in the direction 45° to RD, the starting γ-fibre changes to α-fibre and the overall texture intensity remains unchanged. The lowest value of the Schmid factor of the primary slip system in the presence of (111) [01‾1] texture component of γ-fibre results in the highest value of yield strength of sample S90 as compared to samples S0 and S45. The presence of texture components (111) [11‾0] and (111) [01‾1] of γ-fibre strongly influences the deformation mechanism of the S90 sample by lowering the Schmid factor of slip systems resulting in grain fragmentation and lower value of strain to fracture. The plastic flow curves of the tensile deformed samples in all three directions follow the Ludwigson relationship. The work-hardening rate of the alloy Nb-10Hf-1Ti displays its directional dependence and is well explained by the Kock-Mecking-Estrin analysis.