Influence of Microstructure on Hot Plasticity of Ti-6Al-4V and Ti-5Al-5Mo-5V-1Cr-1Fe Titanium Alloys

摘要

In the paper results of the studies on influence the microstructure of titanium alloys Ti-6Al-4V and Ti-6Al-5Mo-5V-1Cr-1Fe on their hot plasticity have been summarized. Four types of Ti-6Al-4V microstructure - coarse-grained lamellar, fine-grained lamellar, bi-modal (duplex) and globular - and two types of Ti-6Al-5Mo-5V-1Cr-1Fe microstructure - coarse and fine-grained lamellar - were examined. Tests were carried out on torsional plastometer at 900-1050℃ for Ti-6Al-4V and at 800-900℃ for Ti-6Al-5Mo-5V-1Cr-1Fe alloy, at the strain rate of 0.04, 0.4 and 4.0 s~(-1). Influence of microstructure on maximum plastic flow stress σ_(pm) and corresponding strain ε_m was determined. It was found that in the case of Ti-6Al-4V fine-grained lamellar microstructure and for Ti-6Al-5Mo-5V-1Cr-1Fe alloy coarse-grained lamellar microstructure provides highest plasticity in the range of deformation temperature and strain rates applied. Changes in alloys microstructure caused by hot plastic deformation were examined using LM and TEM techniques.