Correlation Between Diagrams of Isothermal and Anisothermal Transformations and Phase Composition Diagram of Hardened Titanium Alloys

Abstract

A brief review of works devoted to phase transformations in titanium alloys and published by the authors during a long period and of recent publications on the topic is presented. When plotting phase diagrams of hardened titanium alloys (metastable diagrams) the authors used as a basis their relationship to the equilibrium diagrams and the transformations of the β-phase of various compositions during hardening from the β-range temperatures. After studying the structure of hardened alloys they investigated their transformations during aging, isothermal treatment, and continuous cooling from the β-range temperatures. Using the interrelation between the phase diagrams of hardened alloys and the phase transformations of β-phase under various kinds of heat treatment the authors developed theoretical diagrams of isothermal and anisothermal transformations, which were later confirmed by experimental diagrams for pilot and commercial alloys. The suggested classifications of diagrams of isothermal and anisothermal transformations are applicable to titanium alloys of various structural classes with allowance for the coefficient K _β of stabilization of the β-phase.