Sumitomo Metal Industries, Inc.

Toshiba Ceramics Co., Ltd.

Sei Hiraki

Akihiro Yamanaka

Toshihiko Murakami

Nobuhiro Okada

Etsuhiro Hasebe

Seiji Kumakura

Yoshihiko Higuchi

Yoichiro Mochizuki

Tetsuro Fushimi

Tatsuo Kanai

Kouji Takatani

Hidetoshi Suwa

Syuji Nakai

Kazuo Okamura

Kazumi Arakawa

Takao Suzuki

Toshiyuki Hirao

Kenji Sugiura

Moriki Hashio

Tadasu Takigawa

Tatsuya Shimoda

Takashi Kanazawa

Sadamichi Kaseda

Satoshi Kuroki

Ken Nakai

An electromagnetic stirrer for stirring molten steel of the liquid core in a width-wise direction of the slab includes an iron core disposed with its length-wise axis along a width-wise direction of slab, and a plurality of exciting coils wound around the outer circumference of and about a length-wise axis of the iron core, wherein two-phase or three-phase alternating current is passed through the coils. The phases of the current in the exciting coils are distributed to impart a stirring flow to the molten that includes flow from the minor sides to the center of the slab or from one minor side to the other minor side with a reversing flow at predetermined time intervals.

Method for continuous casting of steel and electromagnetic stirrer to be used therefor

Disclosed is a continuous casting in which an electromagnetic stirrer is installed upstream, in the casting direction, of the reduction rolling position of a slab, and in which a slab with a liquid core is reduced in thickness, wherein by imparting a collision flow forming-type stirring and a uni-directional alternating flow forming-type stirring, molten steel with concentrated segregation elements is stirred and diffused in a width-wise direction of slab, whereby a slab stabilized in center segregation qualities can be produced over long-time casting operation. Since the stirring flowing pattern is selectively imparted by means of the same electromagnetic stirrer, it is effective to decrease facility and equipment costs, improve maintainability, and extensively cope with various casting conditions. The continuous casting method stably ensures excellent center segregation qualities over a long time in casting of high-strength steel with high crack susceptibility or steel grade for extremely thick plate product.

A steel sheet with a thickness of at least 0.30 mm is made of an ultra-low carbon steel with a chemical composition including C: at most 0.010%, Si: at most 0.5%, Mn: at most 1.5%, P: at most 0.12%, S: at most 0.030%, Ti: at most 0.10%, Al: at most 0.08%, and N: at most 0.0080%. The total number of non-metallic inclusions observed under a microscope in sixty fields in a sample prepared in accordance with JIS G0555 is at most 20. During manufacture of the steel, the amount of FeO+MnO in slag in a ladle at the time of continuous casting is controlled to at most 15%, and the throughput at the time of casting is made at most 5 tons per minute. The steel sheet does not develop pin hole defects or press cracks caused by inclusions when used for applications such as motor housings or oil filter housings requiring severe press forming.

Method of manufacture of ultra-low carbon steel

A continuous casting method is demonstrated, in which a slab including a liquid coreis bulged and then reduced in its thickness with a reduction roll pairin which case, the uppermost surface of the lower rollin the reduction roll pairis located at a higher level than the lower pass lineof the slab. With this method, the slab can be efficiently reduced in its thickness without any loss of reduction force and the generation of segregation can be suppressed at the center area of the slab in the thickness direction. A continuous casting apparatus according to the invention is suitable for carrying out the continuous casting method according to the invention. A slab produced by the method according to the invention has good quality, since the segregation at the center area can be improved over the entire width in which the liquid coreis included.

Continuous casting method, continuous casting apparatus and continuously cast steel slab

A steel sheet with a thickness of at least 0.30 mm is made of an ultra-low carbon steel with a chemical composition including C: at most 0.010 %, Si: at most 0.5 %, Mn: at most 1.5 %, P: at most 0.12 %, S: at most 0.030 %, Ti: at most 0.10 %, Al: at most 0.08 %, and N: at most 0.0080 %. The total number of non-metallic inclusions observed under a microscope in sixty fields in a sample prepared in accordance with JIS G0555 is at most 20. During manufacture of the steel, the amount of FeO&plus;MnO in slag in a ladle at the time of continuous casting is controlled to at most 15 %, and the throughput at the time of casting is made at most 5 tons per minute. The steel sheet does not develop pin hole defects or press cracks caused by inclusions when used for applications such as motor housings or oil filter housings requiring severe press forming.

Ultra-low carbon steel sheet

An integrated submerged entry nozzle for thin slab continuous casting has a plate member 12 corresponding to the lower plate of a slide gate and a nozzle member 11 having a flat molten steel passage section in the part to be submerged into molten steel of at least the tip, the both 11. 12 being integrated together by the use of an organic adhesive. The plate member 12 and the nozzle member 11 are separately formed followed by baking or firing, the both 11, 12 are adhered together by the use of an organic adhesive, the adhesive is dried, the outside is covered with a shell, and refractory mortar is filled in the space. Thereafter, a refractory ring 28 is adhered in such a manner as to cover the inside of the adhesive joint part followed by drying.

Integrated submerged entry nozzle and its manufacture

In a flat casting nozzle 10 having a taper 13, the position of the terminal end 14 of the taper 13 formed on the long edge side and the position of the terminal end 17 of a taper 16 formed on the short edge side are mutually shifted.

Flat formed submerged entry nozzle for continuous casting of steel

Process for continuously casting thin slabs

A silicon aluminum oxynitride containing refractory for use in continuous casting is placed between a mold and a tundish and is formed by sintering an admixture of silicon nitride (Si.sub.3 N.sub.4), aluminum nitride (AlN), boron nitride(BN), and a mineral clay. The refractory further includes aluminum oxide(Al.sub.2 O.sub.3).

Refractory for continuous casting

Growing community of inventors

Kashima, Japan

Sei Hiraki