Managing Executive Officer, General Manager, Sales Dept. No. 3. Koyo YANAGAWA

Akimoku Steel Casting Co., Ltd. Tetsuyoshi KASAI
Ceratechno Co., Ltd. Yuichi TAKAKURA

This article describes the history of steel ladle refractory improvement implemented in Akimoku steel Co., Ltd. in association with Ceratechno Co., Ltd. While newly developed unfired alumina-magnesia brick ALTIMA showed a much smaller wear rate, it wasn’t enough to extend its service life. Thanks to another several technological developments such as inhibition of steel skull adhesion, improvement of well block durability and suitable application of troweling repair, its service life improved from 100 heats to 180 heats, resulting in 47 % reduction in the overall specific cost of steel ladle refractories. (Reprinted from “Steel Casting and Steel Forging”, No.550, pp.18-25 (2019) (Published by Steel Casting and Forging Association of Japan). (English translation is performed by Shinagawa Refractories))

Masafumi NISHIMURA and Koji ASAKAWA

This report summarizes the transition of monolithic refractory materials applied to steel ladles of Japanese integrated steel mills. Zircon castable was the first monolithic material that showed successful result. After that, in accordance with the intensification of secondary metallurgy carried out in steel ladle, dominant material has been changed to alumina-spinel followed by alumina-magnesia in order to improve resistance to corrosion as well as slag penetration. Currently, durable high density alumina-magnesia castable are widely applied and exhibits satisfying results.

Koyo MURAKAMI, Hisashi TOMIYA and Atsuhisa IIDA

Steel ladles are the vessels that retain a molten steel temporarily to transfer it to steel casting facilities. Ladle bricks, which are installed inside the steel ladles, are required to have various characteristics depending on the application of the ladle and the quality of the steel to be produced. In this article, our distinctive ladle bricks for ladle applications are introduced.

Tsuneyuki IIKUNI, Yoshihisa MORIMOTO and Daisuke TANAKA

Recently, attention is being given to cement free castable using colloidal silica as a binder. In this report, the hot modulus of rupture of a cement free castable was investigated. As a result, it was found that the hot modulus of rupture was greatly improved by adding additive X. The newly developed cement free castable containing additive X was tested in an actual furnace with good results.

Gaku SHIMADA, Atsuhisa IIDA, Masayoshi KAKIHARA and Shohei FURUYA

In this paper, in order to clarify the effect of the grain size composition of MgO on microstructure deterioration, MgO of 1.0 mm or less was screened to prepare samples in which the grain size compositions were changed, and the evaluation was carried out. As the surface area of MgO increased, the weight reduction rate increased, and deterioration of the microstructure was observed accompanied by a reaction. On the other hand, when the permeability was about the same, the weight reduction rate of the samples having a large surface area increased, and it was revealed that the MgO-C reaction had a direct effect on the surface area. It was also suggested that resistance to diffusion of gas out of the brick greatly influenced the healthiness of the brick structure, and the increase in large pores of 6 μm or more had influence.

Isolite Insulating Products Co., Ltd. Fumiyuki YACHI, Yasuo SHIRAISHI and Toshiaki HASHIMOTO

Examples of functional improvement by adding fillers to AES molded products are introduced. The cushioning property of filler added AES molded products was examined. Furthermore, the improvement of shape retention after heating and cooling by adding glass fiber was studied.

Masayoshi KAKIHARA, Ryoma FUJIYOSHI, Shohei KANEKO and Atsuhisa IIDA

Recently, the charging pad of the converter often becomes a bottleneck part due to the increase of scrap size and/or ratio. We have developed an improved MgO-C brick for the charging pad by focusing on the improvement of brick toughness, and obtained excellent results in actual furnaces. The development of high toughness type MgO-C brick and its use results in actual application will be described in this report.

Yuto SUZUKI and Kiyoyuki KOMATSUBARA

Improving thermal shock resistance and suppressing quality deterioration during use are countermeasures for preventing cracking failure at the immersion area of the ladle shroud. We have developed materials with high thermal shock resistance by optimizing the graphite grain size distribution. In this report, we introduce a new ladle shroud immersion part material and its actual results.

Erika NAKATANI and Yukimasa IWAMOTO

Steel grades which have high Al content experience significant changes in mold powder performance as compared with conventional steel grades because of the reaction between the Al in the molten steel and SiO2 in the powder slag during casting. This significant change in mold powder composition causes casting troubles and deterioration in steel quality. It is extremely difficult to design a mold powder for high Al medium carbon steel which can provide stable casting operation and prevention of strand surface cracks even after the powder properties greatly change during casting. In this report, a mold powder for high Al medium carbon steel which can have stable casting operation and an improvement of steel quality is described.

Junya ITO, Shoji TAKAHASHI and Yukimasa IWAMOTO

The technologies of near net shape casting of steel products have been improving, and there are many thin slab casters operating around the world. Mold powder development for thin slab casting is also progressing for improvement of operation and steel quality. In this report, a summary of the characteristics of the mold powder is described along with the introduction of new technologies.