Superplastic Isothermal Forging of TiAl-Based Intermetallic Compound

摘要

TiAl-based intermetallics have excellent characteristics, such as low density, high strength and good resistance to oxidation, but they also have some weak points, such as low ductility and poor workability. Isothermal forging offers the potential of forming materials from basic-shaped performs to near-net-shaped products in a single process because of the superplasticity of the materials. In order to study the hot workability of gamma-Met 300, a TiAl-based intermetallic, isothermal compression tests were carried out. As a result, it was found that the material shows superplasticity in the strain rate range of 5 X 10~(-4)s~(-1) to 2 X 10~(-3)s~(-4) at 1423 K, and a 1 X 10~(-4)s~(-1) to 2 X 10~(-3)s~(-1) at 1473 K. A forging test of the material from a cylindrical preform to a disk shape with a boss and rim was also carried out. As the result, a sound product that perfectly filled up the die cavity was obtained by isothermal forging at a temperature of 1473 K and at 1 X 10~(-4)s~(-1).