5th International High Manganese Steel Conference - HMNS 2022

Austenitic high manganese lightweight steels emerge as a potential candidate for structural applications in the automotive industry. The precipitation of κ-carbides in these materials upon age hardening treatment offers a great combination of strength, ductility and toughness, while the high Al content (8-11 wt. %) reduces the specific weight. In general, the size of κ-carbides at grain boundaries can be carefully controlled to render them harmless for room-temperature ductility and toughness. However, the effects of nano-sized grain boundary κ-carbides on the material’s mechanical properties under harsh conditions like H environment and low temperatures are less studied. In this work, we address the formation and growth of grain boundary κ-carbides in an austenitic high manganese lightweight steel and their effects on intergranular cracking, using a combination of experimental techniques including atom probe tomography (APT), electron backscattered diffraction (EBSD) and electron channeling contrast imaging (ECCI). The mechanisms of grain boundary decohesion under H and low-temperature conditions, along with their association with early-precipitated grain boundary κ-carbides, are systematically studied. Further alloying and microstructure solutions for enhancing damage resistance in such materials, including boron doping and grain boundary engineering, are also discussed.