Role of oxidation and microstructure constituents on high chromium steel work roll surface degradation

Thermal fatigue tests were carried out to study the influence of oxidation behavior on the degradation progress of a surface layer of high chromium steel. Specimens cut out from the roll shell were subjected to thermal fatigue at temperatures in the range between 500 and 700 °C by using a thermo-mechanical simulator Gleeble 1500D. Our observation was focused on the impact of oxidation as a principal mechanism of degradation of the roll's surface layer, mainly on the characteristics of oxidation propagation (penetration) related to microstructural characteristics and test temperature. Oxidation is considerably accelerated by certain characteristics of eutectic carbides (i.e., their size, composition, their successive arrangement and orientation to the water-cooled surface, etc.) that are essential for the degradation progress which could lead to spalling of parts.