Method for manufacturing titanium ingot

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, and
• S:
• 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).