Sumitomo Metal Industries Limited announced that it has received the minister of economy, trade and industry's prize in the Manufacturing and Production Process Category of the 4th Monodzukuri Nippon Grand Award for development and commercialization of technology to efficiently manufacture high quality very thick steel plate by continuous casting. The award ceremony was held on February 15th 2012 at the National Graduate Institute for Policy Studies in Minato ku in Tokyo.
1. Development Background
Steel plate as thick as 100 mm or more is used for dies, large industrial machinery, bridges, and offshore structures. The steel slightly shrinks when it solidifies. Thus, when slabs, the base metal steel plate, are cast, porosity formed with a large amount of pores of about 2 mm in diameter is formed at the central part of the molten steel. If the steel plate is not too thick, porosity is compressed and does not cause any serious problem. However, when very thick steel plate is manufactured from slabs as thick as about 300 mm by a continuous casting machine for mass production, a reduction ratio that is sufficient to compress porosity is not obtained. This is why slabs made of large section ingots are needed to manufacture very thick steel plates, resulting in low productivity and high costs.
2. Features of Awarded Technology
Sumitomo Metals installed a reduction roll inside a continuous casting machine at Kashima Steel Works and conducted a test to analyze the relationship between solidification and porosity formation. We then found out that the forming of pores can be efficiently reduced when the slab surface is compressed just before the central part of the slabs is completely solidified at the time when there is a sufficient difference in temperature between the cooled surface and the hot central part. This finding has enabled production of very thick plate by continuous casting for mass production. The new technology to reduce porosity forming by reduction within the continuous casting machine has been named the Porosity Control of Casting Slab technology. Development of the PCCS technology has enabled a reduction in production lead time from about three months to less than one month and cut costs significantly.
3. Future Developments
Sumitomo Metals plans to apply the PCCS technology to high grade very thick steel plate for the energy sector, which has high growth potential, and thereby ensure stable quality and short delivery time.
The Monodzukuri Nippon Grand Award was established to recognize the development of monodzukuri and pass it on to the coming era by rewarding those individuals whose achievements are on the cutting edge of monodzukuri. Since 2005, the Ministry of Economy, Trade and Industry and three other ministries have been collectively promoting this award.
