The main links of the cold roll manufacturing process are melting, forging, heat treatment, processing and inspection.
      In the course of cold rolling, the cold roll has to bear a lot of rolling stress. In addition, the welding seam, inclusion and edge crack of the rolled piece have problems, which easily lead to an instantaneous high temperature and make the work roll subject to a strong thermal shock, causes the crack, the stick roll, the spalling even scrap. Therefore, the cold roll should have the ability to resist the cracking and spalling caused by bending stress, torsion stress and shear stress, as well as high wear resistance, high contact fatigue strength, high fracture toughness and thermal impact strength. Therefore, how to improve the service life of roll is always a major problem in roll manufacturing industry.
       The non-destructive testing of roller is usually carried out by ultrasonic flaw detector. In the cold roll inspection standard, the roll body is usually divided into the surface zone, the center zone and the Middle Zone according to the force, and then the critical size of the allowable defects in each zone is specified according to the fracture mechanics principle. The flaw detector should have the knowledge of roll manufacturing so as to judge the nature of the defects, and also the knowledge of roll using, so as to estimate whether these defects may cause service damage under the specific use conditions. Roll Lathes, roll surfacing