Rolling mills have experienced a great deal of progress in the last few years, thanks to evolution in product quality and advances in productivity. The rolling mill rolls play an essential part in achieving such levels of quality and productivity. Rolling steel rolls for long products rolling have been shown to outperform standard cast-iron rolls in wear resistance and surface quality. Surface quality, shape and roughness of the rolled product, are all directly affected by the period of time the roll can be in operation without being removed due to deterioration. Such roll deterioration may be due to wear, oxidation, extensive cracks or even roll fracture. The finishing trains in long products rolling mills are generally composed of four to six in-line stands that are responsible for the successive reductions in rolled material. The rolls in these finishing stands must have good resistance to both wear and cracks - the main forms of degradation in such applications. The use of steel rolls in long products rolling has shown both improved rolling mill productivity and better rolled material quality. This web pages will shows some defects on rolls for cold rolling.

The exact choice of the steel alloy composition used for a steel mill roll, the prediction of its performance as well as the monitoring of its condition in operation are difficult and responsible tasks of metallurgists. Steel mill rolls are very expensive and thus their durability is of fundamental importance. Residual stresses in a roll are the primary factor influencing its durability. Regeneration of a fatigued roll, by grinding off a sufficiently thick layer, may prevent a fracture of the mill and a costly interruption in the process. As the residual stresses in a steel mill roll build up continuously during a campaign it is important to know their level before the installation of a roll in its cage and after a rolling campaign.

Quality control of production has always been a necessity in steel mills. The users of steel set ever increasing requirements on product quality. The purpose of a surface inspection is to detect and classify surface defects that impair product quality with regard to the requirements set by the user. Critical defects are also those which cause production disturbances.

Most common defects found on the roll surface are: Retempered area on roll surface, rehardened area on roll surface, material welding on roll surface, cracks on roll surface, grinding cracks on roll surface, spalling of roll surface, hair cracks on roll surface, crushing of roll surface, cracks on the radial side of roll, rolling at end of working roll surface, imprinted particle in roll surface, failure of roll, failure of roll neck and corrosion pits on roll surface.