GSB Graphitic Steel Base Rolls
GSB Graphitic Steel Base is different to conventional steel base in that all of the carbon is not present as carbide. By modification of the alloy content and suitable heat treatment, a controlled amount of fine flake graphite particles are dispersed throughout the structure of the roll. As with conventional Steel Base, GSB Graphitic Steel Base is a hypereutectoid steel with a carbon content between %0.9 and %2.4. Wear resistance is principally derived from carbides created during casting and refined during heat treatment.
The matrix structure can be either spheroidized or lamellar pearlite depending on the whether a soft anneal or a stress relief anneal is carried out.
The presence of the graphite improves the fire-crack resistance of the roll and reduces thrust collar wear and the side wear which occurs during indirect reduction. Free graphite reduces the impact of thermal shocks by means of improved dissipation of heat from the surface to the core during the heating cycle and from the core to the surface during the cooling cycle of the roll. It also promotes a finer and more controlled fire-crack pattern.
The grade chosen for an application will have sufficient carbide in its structure to ensure that its wear resistance is high. Grades with higher carbon contents exhibit larger conglomerations of carbide which appear almost continuous.
The virtually constant hardness and wear resistance across the barrel diameter permits Graphitic Steel Base rolls to be used for almost any size of section, especially in applications where wear resistance is required and fire-cracking is a problem.