Hitachi Metals, Ltd.

Ken-ichiro Hara

Etsuo Fujita

Setsuo Mishima

Hidemi Takao

A method for producing a steel ingot, which comprises an Mg oxide forming step of preparing a molten steel containing Mg in an amount sufficient for the molten steel to have an oxide composition having MgO as a primary component and a dissociation step of keeping the pressure of the atmosphere around the molten steel to be lower than that in the Mg oxide forming step, to thereby dissociate MgO to Mg and oxygen and reduce the content of Mg in the steel to 50% or less of that in the Mg oxide forming step through the diffusion thereof into a gas phase. A preferred method further involves a solidifying step.

Method for producing steel ingot

Disclosed is a method of producing maraging steel, which includes producing a consumable electrode for vacuum remelting; and subjecting the consumable electrode to the vacuum remelting. The consumable electrode contains not less 5 ppm Mg. Disclosed is also a maraging steel containing, by mass %, at least, from more than zero to less than 10 ppm Mg, less than 10 ppm oxygen, and less than 15 ppm nitrogen. The steel contains also nitride inclusions having a maximum length of not more than 15 &#x3bc;m and oxide inclusions having a maximum length of not more than 20 &#x3bc;m. Regarding the oxide inclusions, a content rate of spinel form inclusions having a length of not less than 10 &#x3bc;m to a total content of the spinel form inclusions having a length of not less than 10 &#x3bc;m and alumina inclusions having a length of not less than 10 &#x3bc;m exceeds 0.33 (i.e. 33%).

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Myrtle Beach, SC, United States of America

Ken-ichiro Hara