Melting, forging, heat treatment, processing and inspection are the main processes of cold roll manufacturing.
Cold roll in the process of working under a lot of stress and rolling, rolling, weld inclusions, edge crack problems, easily lead to instantaneous high temperature, the working roll by the strong thermal shock, causing cracks, roll sticking, peeling or even scrapped. Therefore, the cold roll resistance due to bending stress, torsion stress, shear stress caused by cracking and spalling, also have high wear resistance, high contact fatigue strength, high fracture toughness and thermal shock strength etc.. Therefore, how to improve the service life of roller has been a major problem in the roller manufacturing industry.
Nondestructive testing of roller is usually performed by ultrasonic flaw detector. According to the principle of fracture mechanics, the critical size of the allowable defects in the area is divided into the surface area, the central area and the middle zone. In order to determine the nature of the defects, and also have the knowledge of the use of rollers, the flaw detection workers should have the knowledge of the use of rollers to estimate whether these defects can lead to service damage under the specific conditions of use.