K. Linga Murty, North Carolina State University, DMR 0412583

1. Effect Of Alloying And Heat Treatment On The Biaxial Creep Behavior Of Titanium Alloys K. Linga Murty, North Carolina State University, DMR 0412583 • The main objectives of this project are to a) study the effect of alloying and heat treatment on the mechanical and creep anisotropy of Ti alloys, b) investigate the effect of biaxial loading on creep characteristics, c) investigate deformation microstructures with particular emphasis on dislocation substructure formation during creep, and d) develop microstructure-based creep constitutive equations. • Mechanical anisotropy was studied as a function of test temperature by performing tensile tests along both the rolling and transverse directions on grade I cp-Ti thin sheets. (D. Earp, MNE, 2009). Contractile strain ratios R and P (Fig-top) revealed essentially temperature-independent R with increased P saturating at around 200C. • Creep studies to-date on cp-Ti sheet revealed grain boundary sliding (GBS) at low stresses with the characteristic n=2 and the activation energy for grain boundary diffusion while dislocation climb was identified at higher stresses (U. Elkazaz, MNE, 2009). These results are similar to those reported earlier on Ti32.5Al under biaxial loading (Fig-bottom). Creep tests at lower stresses along with deformation microstructures using TEM are underway. S. Gollapudi, I. Charit and K.L. Murty, “Creep Mechanisms in Ti-3Al-2.5V Tubing Deformed under Closed-end Internal Gas Pressurization,” Acta Mat., 56 (2008) 2406-2419

2. Summer 2008 Summer 2009 Summer 2007 Summer 2006 Effect Of Alloying And Heat Treatment On The Biaxial Creep Behavior Of Titanium Alloys K. Linga Murty, North Carolina State University, DMR 0412583