Nippon Steel Corporation

Nippon Steel Sumitomo Metal Corporation

Katsuhiro Sasai

Hiroshi Harada

Wataru Ohashi

Eiichi Takeuchi

Takehiko Toh

Hajime Hasegawa

Keisuke Fujisaki

Tooru Matsumiya

Junji Nakashima

Yoshiaki Kimura

Kenichi Yamamoto

Kaoru Kawasaki

Masashi Sakamoto

Hideaki Yamamura

Yui Ito

A continuous casting apparatus for a multilayered slab includes a ladle having a molten steel supply nozzle; a tundish having a first retention portion that receives supply of the molten steel from the ladle through the molten steel supply nozzle and has a first immersion nozzle and a second retention portion that is adjacent to the first retention portion with a flow path interposed therebetween and has a second immersion nozzle; an addition mechanism that adds a predetermined element to the molten steel in the second retention portion; and a casting mold that receives supply of the molten steel from the tundish.

Continuous casting apparatus and continuous casting method for multilayered slab

A high-strength steel sheet includes: 0.03 to 0.20% of C, 0.08 to 1.5% of Si, 0.5 to 3.0% of Mn, 0.05% or less of P, 0.0005% or more of S, 0.008 to 0.20% of acid-soluble Ti, 0.0005 to 0.01% of N, more than 0.01% of acid-soluble Al, and 0.001 to 0.04% of one or both of Ce and La in terms of mass %; and the balance including Fe and inevitable impurities. The ratio of (Ce+La)/acid-soluble Al is equal to or more than 0.1 and the ratio of (Ce+La)/S is in the range of 0.4 to 50 in a mass base, and the density of the number of inclusions, having a circle equivalent diameter of 2 &#x3bc;m or less, which are present in the steel sheet is equal to or more than 15/mm.

High-strength steel sheet and method of producing molten steel for high-strength steel sheet

The present invention provides ultralow carbon thin gauge steel sheet and a method for producing the same where coalescence and growth of inclusions in the molten steel are prevented and the inclusions are finely dispersed in the steel sheet, whereby surface defects and cracks at the time of press forming are prevented, growth of recrystallized grains at the time of continuous annealing is promoted, and a high r value (r value&#x2267;2.0) and elongation (total elongation&#x2267;50%) are exhibited, that is, ultralow carbon thin gauge steel sheet excellent in surface conditions, formability, and workability comprised of, by mass %, 0.00030.003%&#x2266;C&#x2266;0.003%, Si&#x2266;0.01%, Mn&#x2266;0.1%, P&#x2266;0.02%, S&#x2266;0.01%, 0.0005%&#x2266;N&#x2266;0.0025%, 0.01%&#x2266;acid soluble Ti&#x2266;0.07%, acid soluble Al&#x2266;0.003%, and 0.002%&#x2266;La+Ce+Nd&#x2266;0.02% and a balance of iron and unavoidable impurities, said steel sheet characterized by containing at least cerium oxysulfite, lanthanum oxysulfite, and neodymium oxysulfite.

Thin gauge steel sheet excellent in surface conditions, formability, and workability and method for producing the same

The present invention provides a low carbon steel sheet and a low carbon steel slab on which formation of surface defects can be surely prevented by preventing aggregation of inclusions in the molten steel and finely dispersing inclusions in the steel sheet or slab, and a process for producing the steel sheet and slab. The present invention provides a process comprising the steps of decarburizing a molten steel so as to produce a carbon concentration of up to 0.01% by mass, pre-deoxidizing the molten steel by adding Al thereto so as to produce a dissolved oxygen concentration from 0.01 to 0.04% by mass, adding thereto Ti and at least La and/or Ce, and casting the molten steel, and a steel sheet and a steel slab obtained by the process.

Low carbon steel sheet and low carbon steel slab and process for producing same

A cast slab has a negative segregation zone composed of a multilayer structure of negative segregation layers disposed between dendrite or crystalline layers. The dendrite or crystalline layers are a deflection structure caused by vibration during formation of the cast slab. The negative segregation layers have a distance between them of not more than 2 mm and the number of negative segregation layers is not less than 3. The cast slab has an equi-axed crystal ratio of not less than 50% inside the multilayer negative segregation zone.

Method for casting molten metal, apparatus for the same, and cast slab

The present invention provides a continuous casting method in which vibration is given to molten metal by a shifting magnetic field so that the equi-axed crystal ratio can be enhanced and the equi-axed crystals can be made fine without generating surface defects caused by powder trapping. Further, the present invention provides an apparatus to which the continuous casting method is applied. Furthermore the present invention provides a cast slab produced by the above method and apparatus. The method of casting molten metal comprises the following steps: pouring molten metal into a mold and solidifying it in the mold while applying an electromagnetic force, which is generated by an electromagnetic coil arranged in the proximity of a molten metal pool in the mold, upon the molten metal; and vibrating the molten metal, which has been solidified in the mold while being cooled and solidified, by a shifting magnetic field generated by the electromagnetic coil so that the molten metal is accelerated by a high intensity and a low intensity of acceleration in a range not exceeding a predetermined flow velocity when the directional vectors of high acceleration and low acceleration in the same direction or in the opposite direction are combined with each other.

Growing community of inventors

Futtsu, Japan

Katsuhiro Sasai