As Europe continues to work towards reducing its greenhouse gas emissions, the steel industry is exploring cleaner energy alternatives. One promising solution is to replace natural gas with hydrogen in the furnaces used to heat steel prior to shaping. But what effect does this change have on the steel itself?
A recent publication by Francis Gyakwaa, D.Sc.(Tech), a researcher at the University of Oulu involved in the Twinghy project, addresses this question. The research team investigated how different hydrogen-based fuel mixtures influence the formation of oxide scale — a rust-like material that forms on steel surfaces during heating.
When steel is heated in a furnace, it reacts with the oxygen in the air to form this layer. This layer is normal, but if it becomes too thick or uneven, it can reduce the quality of the final product and lead to material loss.
Therefore, understanding how hydrogen affects this process is crucial to ensuring that the transition to cleaner fuels does not compromise the quality of steel.
The research involved testing five different fuel mixtures, ranging from 100% natural gas to 100% hydrogen, under realistic industrial conditions. Two types of low-carbon steel were used to observe their reaction.
The main takeaways are as follows:
– Hydrogen increases oxidation slightly. The oxide layer became slightly thicker when hydrogen was used instead of natural gas, but the change was moderate.
– Oxygen levels are critical: higher oxygen levels in the furnace led to increased oxide formation, particularly when hydrogen was present.
– There were no major changes in oxide type. The types of oxides formed (mainly magnetite and wüstite, which are common iron oxides) remained consistent across all fuel types.
These findings support the objectives of the Twingly project, which aims to make hydrogen-based steel production a reality. By understanding the small yet significant changes that hydrogen brings, researchers and industry leaders can collaborate to create a cleaner and more sustainable future. This is a promising step towards decarbonising the steel industry, one of the largest industrial sources of CO₂ emissions in Europe.
Read the full publication here: