Hitachi Metals, Ltd.

Hidemi Takao

Etsuo Fujita

Setsuo Mishima

Ken-ichiro Hara

Takeo Mizuguchi

Kenichiro Hara

Makoto Ishihara

Tetsunori Hayafuji

Ken-Ichiro Hara

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%).

Maraging steel and method of producing the same

A Fe--Ni based alloy sheet having superior surface characteristic and superior etchability, essentially consisting, by weight, of 30 to 50% nickel, 0.05 to 0.5% manganese, 0.001 to 0.02% silicon, not more than 0.0015% aluminum, not more than 150 ppm oxygen, and the balance iron and incidental impurities, the value of Mn content(weight %)/Si content (weight %) being not less than 20. Preferably, silicon content is 0.001 to 0.01%, aluminum being not more than 0.0005%, oxygen being not more than 90 ppm, sulfur which is one of important impurities being not more than 0.005%, and boron which is one of important impurities being not more than 0.005%.

Fe-Ni based alloy sheet having superior surface characteristic and

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Matsue, Japan

Hidemi Takao