HEAT TREATMENT OF ALPHA-BETA TITANIUM ALLOY FOR ISOTHERMAL WORKING

摘要

PURPOSE:To improve elongation characteristics of under-mentioned alloy and to increase ductility at the time of isothermal working to a great degree, by subjecting an alpha-beta Ti alloy to heating at a specific temp. of the beta-transformation point of the alloy or below, to rapid cooling, and to isothermal working in a specific temp. region of the beta-transformation point or above. CONSTITUTION:In order to improve the hot workability of the alpha-beta Ti alloy such as the one of Ti-6%Al-4%V, Ti-6%Al-4%V-2%Sn, etc., the above Ti alloy is subjected to, prior to isothermal working in the temp. region between the beta-transformation point and (beta-transformation point -150 deg.C), heat treatment consisting of heating and holding at the temp. between (isothermal working temp. +20 deg.C) and the beta-transformation point and of rapid cooling at =10 deg.C/min cooling rate. In this way, the ductility in isothermal working of the alpha-beta Ti alloy hitherto considered to be difficult to work is improved and, as a result, working is facilitated.