Effect of MC Type Carbides on Wear Resistance of High Wear Resistant Cast Iron Rolls Developed for Work Rolls of Hot Strip Mills

Abstract

High-speed steel cast-iron rolls were developed around 1990 and have been widely used for the earlier stand of hot strip mills. However, for the later stand of hot strip mills, the use of high-speed steel cast-iron rolls has been limited due to the insufficient crack resistance. Therefore, in order to improve the wear resistance of the later stand, enhanced indefinite chilled rolls in which MC-type carbides of high hardness are crystallized in a conventional indefinite chilled roll has been developed. However, since the wear resistance of enhanced indefinite chilled rolls is significantly inferior to that of high-speed steel cast-iron roll, the development of a new cast iron roll with superior wear resistance applicable to the later stand of hot strip mills was studied. The present development roll has improved wear resistance by increased amount of the high hardness MC-type carbide-forming elements. In addition, the reduction of the carbon equivalent for less amount of eutectic carbide resulted in the reduction of the residual stress down to the same level as the indefinite chilled roll, which improved the crack resistance. As a result, it was confirmed that the wear resistance was improved about three times compared with the conventional indefinite chilled roll. In addition, the results suggest that the wear resistance of work rolls in hot strip mills is greatly controlled by the amounts of MC-type carbides, despite the roll hardness being the same.

Study of a fuse‐polymerised inorganic glassy compound as a hot rolling lubricant

“…The matrix also shows a higher stiffness with an elastic modulus at approximately 291 GPa, materially higher than 210 GPa of the general steel. This is attributed to the finely dispersed hard MC‐type and M 2 C‐type carbides precipitated in the temper process 27,28 . The higher stiffness indicates the higher resistance to elastic deformation, which can ensure the shape precision of the hot rolled products.…”

“…This is attributed to the finely dispersed hard MC-type and M 2 C-type carbides precipitated in the temper process. 27,28 The higher stiffness indicates the higher resistance to elastic deformation, which can ensure the shape precision of the hot rolled products.…”

“…The cost of work rolls is accounting for approximately 15% of the production costs in a hot rolling mill, thus, reducing the wear rate of rolls and prolonging their service lifetime have always been vital 13–15 . Therefore, lubricant is introduced into hot rolling process, and the selection of lubricant becomes a huge challenge, because the lubricant shall not only be able to withstand high temperatures but also be very smart.…”

“…The cost of work rolls is accounting for approximately 15% of the production costs in a hot rolling mill, thus, reducing the wear rate of rolls and prolonging their service lifetime have always been vital. [13][14][15] Therefore, lubricant is introduced into hot rolling process, and the selection of lubricant becomes a huge challenge, because the lubricant shall not only be able to withstand high temperatures but also be very smart. The traditional organic oil, fat, grease, layered graphite, and MoS 2, and those with these as major components will be severely oxidised, pyrolyzed, and even burned off at such high temperature.…”

Effect of Alloying and Microalloying Elements on Carbides of High-Speed Steel: An Overview

“…The type, morphology, distribution, and microstructural characteristics of carbides in high-speed steel are influenced by alloying elements. As a result, carbides have been the focus of high-speed steel research for more than a century, dating back to the first introduction of the material due to their impact on the engineering performance of high-speed steel [4][5][6][7][8][9][10][11].…”