Hitachi Metals Wakamatsu Ltd. (Kitakyushu City, Japan):

Hattori T., Mag. Eng., Gen. Manager, Engineering Division, e-mail: toshiyuku.hattori.pt@hitachi-metals.com
Oda N., Mag. Eng., Seior Engineer, Casting Section

Hitachi Metals Europe GmbH (Düsseldorf, Germany):

Maeda N., Bach. Eng., Gen. Manager, Roll European Branch

In spite of excellent wear resistance, conventional highspeed steel rolls (HSS rolls) have only been applied in front or middle stands, not in the later ones of hot strip mill finishing trains due to their inferior crack resistance. Consequently, indefinite chilled rolls (ICDP) still have to be used in the later stands, which is one of the major impediments to total mill productivity increase due to frequent roll changes of ICDP. The new type of HSS roll has the same level of strip sticking resistance with ICDP, which is missing in the conventional HSS rolls, consequently performed comparable crack resistance as ICDP. Combined with more than two times of wear resistance compared with E-ICDP (ICDP enhanced with MC-type carbide), this new type of HSS roll is expected to be used for more than twice the amount of rolling as E-ICDP in the later stands, contributing to production increase, labour saving and higher productivity for hot strip mill production. From laboratory evaluation, it can be concluded that the new type of HSS roll is expected o show more than twice the wear resistance and same level of crack resistance as E-ICDP, which is the target of the development. A new type of HSS roll for later stands in hot strip mills which has same level of anti-crack and antisticking resistance with conventional and enhanced ICDP and superior wear resistance to them has been developed. Patent applications of the development have been completed in countries all over the world.

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