Comparable scale formation and decarburization of low-alloy steels during semi-industrial reheating in hydrogen/air versus natural gas/air at 1100°C

To meet the Paris Agreement, steel plants must reduce CO 2 -emissions, for example by retrofitting reheating furnaces to hydrogen/air operation. During reheating the steel grades are exposed to an oxidizing atmosphere at elevated temperatures, resulting in concurrent scale formation and decarburization. While research on scale formation under hydrogen/air combustion atmosphere is increasing, studies on decarburization under relevant reheating conditions are limited. Here, we examine the scale formation of five and the decarburization of two low-alloy steel grades that were reheated at 1100 °C in a hydrogen/air and a natural gas/air atmosphere using a semi-industrial setup. We demonstrate that switching the fuel results in a maximum 15 % increase in scale formation. The scale morphology remains unchanged. We also show that the decarburization depth of the two higher-carbon steels is similar in both combustion atmospheres. Thus, switching a reheating furnace to hydrogen/air combustion is expected to yield products similar to those produced under natural gas/air operation.