Effects of Forging and Heat Treatment Conditions on Mechanical Properties of a High Strength Titanium Alloy, Ti-17

Abstract

This report was to study the dependence of mechanical properties of a Ti-17 forging on processing variables such as final hot working reduction rate and its temperature, and heat treatment.
The major results obtained are as follows :
(1) In the case of equiaxed α microstructures, a larger final forging reduction was desirable for raising ductility and also unnotched fatigue strength, and on the other hand a lesser one greatly improved fracture toughness. Putting these results together, it was concluded that the way of raising fracture toughness would be favorably adopted.
(2) Double solution heat treatment was proved a better way to improve fracture toughness than conventional single solution treatment. Basic data for solution and aging temperature for controlling mechanical properties were acquired.
(3) β-processed acicular microstructure, which gave the best fracture toughness, showed inferior ductility in the transverse direction of a forged bar, of which problem needs further studies to solve.