CHARACTERIZATION OF SOLUTION ANNEALING BEHAVIOUR IN TITANIUM ALLOYS BY ULTRASONIC VELOCITY MEASUREMENTS

摘要

Ultrasonic velocity measurements have been carried out in two titanium alloys, Ti-6Al-4V and Ti-4.5Al-3Mo-lV (VT14), solution annealed at different temperatures starting from 923 K to 1323 K at an interval of 50 K for 1 h followed by water quenching. In both the Ti-alloys, ultrasonic longitudinal and shear wave velocities have been found to decrease with increase in solutionizing temperature up to about 1123 K, and beyond that it is found to increase. Ultrasonic velocities have been found to be constant in the VT14 alloy specimens solution annealed at above 1223 K (β transus temperature) and in Ti-6Al-4V alloy above 1273 K (β transus temperature). The present study revealed for the first time that ultrasonic velocity measurements can be used not only for the characterization of microstructural features but also for the identification of |3 transus temperature in Titanium alloys. Further, it has been found that ultrasonic shear wave velocity is a better parameter for microstructural characterizations in titanium alloys.