New Trends in Hot Strip Mill Roughing Mills: Characterization of High Chromium Steel and Semi-HSS Grades

AbstractAuthors AIST.org February 2012 ✦ 1 New Trends in Hot Strip Mill Roughing Mills: Characterization of High Chromium Steel and Semi-HSS Grades Two alloys grades for work rolls used in the roughing stand of Hot Strip Mill — high chromium steel (HCS) and semi-high-speed steel (semi-HSS), In this paper, the new semi-high-speed steel grade is studied. Jacqueline Lecomte-Beckers head of metallic materials science unit, aerospace and mechanics department, University of Liege, Liege, Belgiumjacqueline.lecomte@ulg.ac.be T. Jerome Tchuindjang researcher, MMS unit, University of Liege, Liege, Belgiumj.tchuindjang@ulg.ac.be This article is available online at AIST.org for 30 days following publication. I n the early 1980s, chrome steel work roll grade was developed by European rollmakers and has, since then, been introduced in most of roughing stands of hot strip mills (HSMs), as well as into the early fin-ishing stands of compact strip mills. As of 2010, chrome steel grade was still a standard grades in many HSMs over the world, as can be seen in Figure 1. The ever-increasing require-ments for roughing mills, in terms of cost/performance ratio, includ-ing higher throughput, improved product quality and higher safety standards, prompted European rollmakers in the early 1990s to develop a new roll grade for rough-ing stands, which is known as semi-high-speed steel (semi-HSS). This new grade was considered to be a real revolution in terms of roll performance in nearly all aspects of the required behavior. Semi-HSS acquired a strong posi-tion, especially in Western European HSMs. However, some applications like stain-less and special steel rolling have shown interest of fur-ther development to overcome some insufficiencies of semi-HSS. A special high-speed steel (HSS) grade for roughing mill application was developed to meet this new challenge in the late 1990s (see the history of work roll development in Figure 2).