Oxidation and wear behavior of high-speed steel and semi-high-speed steel used in hot strip mill

Depending on various properties such as hardness, roughness, friction coefficient, wear resistance, and oxidation behavior, different grades of steel can be used in hot strip mills. In this paper, two grades were investigated: one grade of semi-high-speed steel and one grade of high-speed steel. They differ in their chemical composition, principally the carbon and the chromium content, and the presence or not of other alloying elements such as vanadium, niobium, and tungsten. Their oxidation behavior was studied at 576 °C and 600 °C, temperatures reached in the F1 finishing stand and the roughing stand, respectively, by high-temperature oxidation tests in a wet atmosphere. The sliding wear resistance was followed by pin-on-disc experiments. The evolution of the microstructure was observed by optical and scanning electron microscopies. The oxides formed on the surface of the samples were analyzed by XRD and EDS. The thickness of the oxide layers and the mass gain were measured from oxidation tests. The results showed that for both grades, the surface roughness Ra after oxidation tests is high enough to prevent slipping. The low friction coefficient will increase the wear resistance of the roll. The hardness of the steel grades decreases but remains high enough to ensure wear resistance. Consequently, those grades can be used in the roughing stand or the F1 finishing stand of hot rolling mills.