RECENT TRENDS IN HOT STRIP ROUGHING MILLS: HIGH CHROMIUM STEEL VERSUS SEMI-HSS

compared. The first grade known as High Chromium Steel (HCS) is presently the most
widely used alloy for such an application, while the second one known as semi-High Speed
Steel (semi-HSS) is the new grade developed to improve the overall performance of the
work roll in the roughing stands of the HSM. In the present paper, the new semi-HSS grade
is studied starting from three chemical compositions closed one to another, the variation in
the alloying elements is intended to assess, on one hand the effect of a small increase of
the carbon content, and on the other hand the influence of the addition of a strong MC
carbide forming element. Furthermore, corrosion behavior and performances of the work
rolls in service are compared. Various techniques are used in order to characterize both
grades, such as Differential Thermal Analysis (to determine phase transformations
temperatures, the crystallization behavior and the interval of solidification), hardness
measurements, optical microscopy, scanning electron microscopy associated with energy
dispersive X ray spectroscopy (to determine the nature and the composition of phases,
especially matrix and carbides). Finally micro-macro relations between the nature of the
microstructure and the properties of High Chromium Steel and semi-HSS rolls grades in
service conditions could be established.