A comparative experimental analysis of the scale formation of various steel grades during reheating under hydrogen and natural gas air–fuel and oxy–fuel combustion conditions
Stefan Schwarz, Georg Daurer, Benjamin Plank, Hans-Günter Krull, Anne Szittnick, Mohammed Ali Lakhdari, Sébastien Collin, Pascale Gasca, Éric Chauveau, Christian Deville-Cavellin, Martin Demuth, Christian Gaber, Christoph Hochenauer
Abstract
The presented paper, deals with the influence of natural gas and hydrogen air–fuel and oxy–fuel combustion on scale formation. A semi-industrial scale furnace with a multi-fuel, multi-oxidizer burner was used to generate diverse combustion atmospheres, which were utilized to heat steel samples of twelve distinct steel grades to 1250 °C. This simulates industrial steel reheating. The weight gains due to oxidation during the reheating was measured. Subsequently, the samples were metallurgically analyzed to identify potential discrepancies in the quality of the reheated steel. Via light microscopy, scanning electron microscopy and electron probe micro-analysis, the structure and composition of the formed scale layer was scrutinized. The results showed, that weight gains were more dependent on the oxidizer, than on the fuel, resulting in a maximum increase of 63 % for H2-O2 combustion. Overall, the metallurgic results, showed no significant changes other than the thickness and the porosity of the scale layers. • Scale formation investigation of austenitic, ferritic and martensitic steel grades. • Simulated reheating process in a semi-industrial scale furnace. • Investigation of scale formation under H2 and NG air- and oxy–fuel conditions. • Weight gain comparison, SEM and EPMA examination of heat treated samples. • Comparison of hydrogen and natural gas reheating shows no significant differences.