A Cryogenic Treatment System for Treating Large Rolls

Cryogenic treatment is a supplementary process of traditional heat treatment which has been acknowledged for many decades as an effective method for increasing wear life, dimensional stability and mechanical properties such as yield strength, hardness etc.A cryogenic treatment system for treating large rolls has been designed, built and tested. Liquid nitrogen has been employed to provide cooling capacities; and the temperature can be controlled from -180 ̊C to the room temperature with an accuracy of ±3 ̊C by the developed temperature controller. A 9Cr3Mo roll with the size of Φ260 mm has been cryogenic treated in this developed system. The test results show that most of the residual austenite would be changed into martensite after cryogenic treatment, which contributes to an improvement in hardness and dimensional stability.