Gustav Hultgren
Gustav will use the expertise he gained during his PhD on fatigue and fracture in high-strength steel to address challenges in steel solidification process. In particular, he will study centreline segregation - where the core is chemically distinct, with altered mechanical properties, in comparison to the outer bulk of the material. Centreline segregation may be more of an issue in steels produced using hydrogen, as hydrogen can make steel more susceptible to embrittlement and failure. Understanding this centreline segregation phenomenon is essential for ensuring the production of high-quality, uniform steel products.
What were you doing before joining Steel for a Fossil Free Future?
Before joining Steel for a Fossil Free Future, I completed my PhD on fatigue and fracture in high-strength steel. My research provided me with extensive knowledge in the mechanical characterisation of welded and cut high-strength steel from a reliability assessment perspective. It also allowed me to collaborate with industrial steel producers and end-users in Sweden, allowing me to gain insights into their challenges. This industry engagement enabled me to focus my research on topics with direct practical benefits, such as contributing to the revision of European standards to extend the use of higher-strength materials.
What will you be doing as a Post Doc?
Within Steel for a Fossil Free Future, my research will focus on quantifying the mechanical properties of steel and their potential degradation due to centreline segregation. Centreline segregation occurs during the steel solidification process and can result in a chemically distinct core with altered mechanical properties. The uneven distribution of alloying elements and impurities may reduce the steel’s strength and increase its brittleness, making it more susceptible to cracking under stress. Understanding this phenomenon is essential for ensuring the production of high-quality, uniform steel products.
What challenges will your Post Doc work contribute to solving?
Centreline segregation has been shown to impair fracture toughness and hydrogen embrittlement resistance locally, particularly in higher-strength steels. However, these effects are not yet well quantified. This quantification is crucial for the ongoing transition to fossil-free steel production, as it will help ensure that steel quality remains high following the shift to electric arc furnaces and the increased use of recycled steel.
How can your research contribute to address those challenges?
My research will support steel producers in assessing the impact of centreline segregation on mechanical properties before and after the transition to fossil-free production. By improving the understanding of potential variations in mechanical properties due to segregation, my work will help identify ways to minimise these effects from a process optimisation standpoint.
The name of my research project is
"Degradation of Fossil-Free High-Strength Steel Due to Centreline Segregation", a collaboration between KTH, LTU, and SSAB.