High-temperature deformation behavior and microstructural characterization of high-Mn bearing titanium-based alloy

摘要

Ti-Mn alloys exhibit an excellent potential for biomedical applications as well as structural engineering applications, especially in the aerospace industry. In order to control and enhance grain structure during the manufacturing of Ti-Mn alloys and thereby help to enhance mechanical properties such as strength and toughness, we studied the hot-deformation behavior of beta Ti-10Mn alloys. Isothermal compression tests were conducted in the strain rate range of 0.01-10 s(-1) and temperatures in the range of 850-1000 degrees C using a Gleeble thermo-mechanical simulator. High-temperature flow stress curves exhibited discontinuous yielding and pronounced periodic serrations without any strain hardening during compression straining of these alloys. Such peculiar behavior of this alloy is due to active dynamic strain aging in its beta-bcc structure. Metallographic observations by electron-backscattered diffraction (EBSD) analysis revealed that dynamic recovery (DRV) is more active than continuous dynamic recrystallization (CDRX) when the alloy is deformed at high strain rates, i.e. higher than 1 s(-1). Furthermore, the constitutive behavior of the alloy was modeled and the apparent hot-deformation activation energy of the alloy was estimated to be 243 kJ/mol, which is similar to 60% higher than the self-diffusion energy in pure titanium.