The present invention relates to steel sheet realizing both formability and weldability. The steel sheet of the present invention is characterized in that at a surface layer part of a region down to 30 ?m from the surface of the steel sheet in the sheet thickness direction, Al oxide grains are present in 3000 to 6000/mm.sup.2 in number density, the natural logarithms of the particle sizes of the Al oxide grains measured in ?m units are on the average ?5.0 to ?3.5, the standard error is 0.6 or less, and the number of Al oxide grains with deviations of the natural logarithms of the particle sizes from the average larger than 2 times the standard error is 5% or less of the total number of Al oxide grains and at a position of ? of the thickness of the steel sheet, the number density of the Al oxide grains is 1000/mm.sup.2 or less.

A copper alloy sputtering target is formed by a copper alloy including the content of Ca being 0.3 to 1.7% by mass, the total content of Mg and Al being 5 ppm or less by mass, the content of oxygen being 20 ppm or less by mass, and the remainder is Cu and inevitable impurities. A manufacturing method of a copper alloy sputtering target comprises steps of: preparing a copper having purity of 99.99% or more by mass; melting the copper so as to obtain a molten copper; controlling components so as to obtain a molten metal having a predetermined component composition by the addition of Ca having a purity of 98.5% or more by mass into the molten copper and by melting the Ca; casting the molten metal so as to obtain an ingot; and performing stress relieving annealing after performing hot rolling to the ingot.

A copper alloy sputtering target is formed by a copper alloy including the content of Ca being 0.3 to 1.7% by mass, the total content of Mg and Al being 5 ppm or less by mass, the content of oxygen being 20 ppm or less by mass, and the remainder is Cu and inevitable impurities. A manufacturing method of a copper alloy sputtering target comprises steps of: preparing a copper having purity of 99.99% or more by mass; melting the copper so as to obtain a molten copper; controlling components so as to obtain a molten metal having a predetermined component composition by the addition of Ca having a purity of 98.5% or more by mass into the molten copper and by melting the Ca; casting the molten metal so as to obtain an ingot; and performing stress relieving annealing after performing hot rolling to the ingot.

A method of controlling the amount of hydrogen in steel for consistent heat transfer in continuous casting by adding a hydrocarbon to the molten metal. A heat of molten steel is formed in a ladle metallurgy furnace adapted for use in continuous casting. Then, a hydrocarbon is added to the molten metal in the ladle metallurgy furnace in an amount sufficient to increase hydrogen levels in the molten steel for casting. And finally, the molten steel with a desired level of hydrogen is delivered to a caster to continuously cast a steel product.

A method of controlling the amount of hydrogen in steel for consistent heat transfer in continuous casting by adding a hydrocarbon to the molten metal. A heat of molten steel is formed in a ladle metallurgy furnace adapted for use in continuous casting. Then, a hydrocarbon is added to the molten metal in the ladle metallurgy furnace in an amount sufficient to increase hydrogen levels in the molten steel for casting. And finally, the molten steel with a desired level of hydrogen is delivered to a caster to continuously cast a steel product.

A continuous casting process of a steel semi-product is provided. The process includes a step of casting using a hollow jet nozzle located between a tundish and a continuous casting mould. The nozzle includes, in its upper part, a dome for deflecting the liquid metal arriving at the inlet of the nozzle towards the internal wall of the nozzle, defining an internal volume with no liquid metal. A simultaneous step of injecting powder through a hole of the dome occurs. The powder has a particle size of 200 m or less. The dome includes a first device to inject the powder without any contact with the dome and a second device to avoid sticking or sintering of the powder onto the first device.

A continuous casting process of a steel semi-product is provided. The process includes a step of casting using a hollow jet nozzle located between a tundish and a continuous casting mould. The nozzle includes, in its upper part, a dome for deflecting the liquid metal arriving at the inlet of the nozzle towards the internal wall of the nozzle, defining an internal volume with no liquid metal. A simultaneous step of injecting powder through a hole of the dome occurs. The powder has a particle size of 200 m or less. The dome includes a first device to inject the powder without any contact with the dome and a second device to avoid sticking or sintering of the powder onto the first device.

A copper alloy sputtering target is formed by a copper alloy including the content of Ca being 0.3 to 1.7% by mass, the total content of Mg and Al being 5 ppm or less by mass, the content of oxygen being 20 ppm or less by mass, and the remainder is Cu and inevitable impurities. A manufacturing method of a copper alloy sputtering target comprises steps of: preparing a copper having purity of 99.99% or more by mass; melting the copper so as to obtain a molten copper; controlling components so as to obtain a molten metal having a predetermined component composition by the addition of Ca having a purity of 98.5% or more by mass into the molten copper and by melting the

Ca; casting the molten metal so as to obtain an ingot; and performing stress relieving annealing after performing hot rolling to the ingot.

A copper alloy sputtering target is formed by a copper alloy including the content of Ca being 0.3 to 1.7% by mass, the total content of Mg and Al being 5 ppm or less by mass, the content of oxygen being 20 ppm or less by mass, and the remainder is Cu and inevitable impurities. A manufacturing method of a copper alloy sputtering target comprises steps of: preparing a copper having purity of 99.99% or more by mass; melting the copper so as to obtain a molten copper; controlling components so as to obtain a molten metal having a predetermined component composition by the addition of Ca having a purity of 98.5% or more by mass into the molten copper and by melting the

Ca; casting the molten metal so as to obtain an ingot; and performing stress relieving annealing after performing hot rolling to the ingot.

In a continuous casting method for casting aluminum-deoxidized molten stainless steel 1 by using a continuous casting apparatus 100 in which a long nozzle 3 extending into a tundish 101 is provided at a ladle 2, the molten stainless steel 1 is poured into the tundish 101 through the long nozzle 3, while the spout 3a of the long nozzle 3 is being immersed in the molten stainless steel 1 that has been poured, and the molten stainless steel 1 in the tundish 101 is poured into a casting mold 105. A TD powder 5 is sprayed so that the powder covers the surface of the molten stainless steel 1 in the tundish 101, and nitrogen gas is supplied around the molten stainless steel 1. A calcium-containing material is added to the molten stainless steel 1 in a state other than a state of retention in the tundish 101.