| 主权项 |
1. A method for manufacturing a titanium alloy ingot (the titanium alloy being allowable to be pure titanium), comprising:
(a) melting a titanium material or titanium scrap material (hereinafter referred to as “titanium material”) by a cold crucible induction melting (hereinafter referred to as “CCIM”) in such a manner that the following expression (1) can be satisfied:
y≧700×A−1.2 (1) wherein A=P/(V/S) wherein
y: the period [min] for the melting,A: a thermal balance parameter,P: the applied electric power [kW] in the CCIM,V: the volume [m3] of the melted titanium, andS: the surface area [m2] of the melted titanium, (b) supplying, after (a), the resultant titanium material, which has been melted (hereinafter referred to as the “melted titanium material”), to a cold hearth, and separating an inclusion having a large specific gravity which is more than 5 g/cm3 (hereinafter referred to as “HDIs”) by precipitation inside the cold hearth while a plasma jet is blown onto or an electron beam is radiated onto a surface of the melted titanium material, thereby yielding a titanium alloy, and (c) supplying, into a mold, the titanium alloy, in which the inclusion, the specific gravity of which is large, has been separated by precipitation, thereby yielding the titanium ingot, wherein inclusions having a specific gravity of 5 g/cm3 or less and a grain diameter of up to about 15 mm present in said titanium material are decreased in amount such that the proportion is about 1% or less of the starting amount thereof as a result of carrying out (a). |
