Cold mill roll life and flaw detection standards

The main links in the manufacturing process of cold rolls are smelting, forging, heat treatment, processing and inspection.

Cold rolls have to bear a lot of rolling stress during the working process, and problems such as welding seams, inclusions and edge cracks in the rolled piece are easy to lead to instantaneous high temperature, which makes the work rolls subject to strong thermal shock, resulting in cracks, sticking, and peeling off. even scrapped. Therefore, the cold roll should have the ability to resist cracking and spalling caused by bending stress, torsional stress and shear stress, and 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 the roll has always been a major problem faced by the roll manufacturing industry.

Non-destructive testing of rolls is usually carried out with ultrasonic flaw detectors. In the cold roll flaw detection standard, the roll body is usually divided into a surface area, a central area and an intermediate area according to the force, and then the critical size of the allowable defects in each area is specified according to the principle of fracture mechanics. Flaw detectors should have knowledge of roll manufacturing in order to determine the nature of defects, and should also have knowledge of roll use in order to estimate whether these defects may cause service damage under specific conditions of use.