Erik Offerman, together with Carin Emmy Ingrid Christersdotter Öhlund, Jonathan Weidow and Mattias Thuvander, has won the Sawamura Award 2015 for the paper “Effect of Ti on Evolution of Microstructure and Hardness of Martensitic Fe-C-Mn Steel during Tempering.” Their research contributes to the development of resource efficient high strength steel. The award has been given by the Iron and Steel Institute of Japan (ISIJ).
Demands for using martensitic steels for further strengthening of various structural components are increasing recently. Tempering of martensite is usually used to obtain superior strength-toughness balance. To maintain required strength, alloy addition is made to retard softening or obtain secondary hardening by fine precipitation of alloy carbide. However, microstructure change during tempering is complex due to hierarchical substructure of martensite and transition of carbide phase and thus, physically based modeling of tempered microstructure and corresponding mechanical properties is still not sufficient.
The paper has performed quantitative characterization of carbide precipitation and microstructure change in the martensite matrix and hardness change in multi-scale during tempering of microalloyed steels utilizing various experimental methods. Also advanced modeling of carbide precipitation has been proposed. It represents the high standard in characterization of martensite tempering, and simulation made by a model taking various effects into account systematically is in good agreement with the experimental observations. This paper was found to have made important contributions in both of the academic and industrial aspects and as a consequence worthy of the Sawamura Award.