Effect of Alloying and Thermo-Mechanical-Treatment on Anisotropic Creep and Deformation of Ti-alloys

North Carolina State University, Raleigh NC

Investigators

Abstract

This project addresses the influence of thermo-mechanical-treatment (TMT) and alloying on deformation and creep anisotropy of titanium alloys. The research involves characterization of anisotropic biaxial creep of Ti alloys using closed-end internally pressurized thin-walled tubing superimposed with an axial load. The approach is to investigate these behaviors in Ti and Ti- 3Al-2.5V following stress-relief anneal and complete recrystallization. Alloying additions such as Al to Ti result in significant modification of crystallographic texture and operating slip systems. Cold-working leads to grain-shape anisotropy of the otherwise equiaxed grain structure of Rx materials. The effects of these variables on deformation microstructures are to be investigated along with deformation anisotropy following biaxial loading under varied stress-states and stress-levels. Transitions in creep mechanisms and the effect of underlying deformation mechanism(s) on creep anisotropy will also be addressed. Such studies are important for realistic estimates of creep strains and life of these structural materials in service. %%% The project addresses basic research issues in a contemporary topical area of materials science with technological relevance in aerospace, automobile, and chemical sectors where Ti-alloys are used in tube form. An important feature of the program is the integration of research and education through the training of students in a fundamentally and technologically significant area. The project is expected to provide unique opportunities for graduate and undergraduate students to develop strong technical, communication, and organizational/management skills through experiences in a forefront research environment. ***