Correlational research of microstructure characteristics and hydrogen induced cracking in hot-rolled Fe-6Mn-0.2C-3Al steels.

Two-type specimens with different microstructure e.g. A70 contains finer-grained ferrite and austenite, while abundant coarse ferrite is obtained in A30. The different response on hydrogen embrittlement behavior results from the fundamental differences of microstructure. The dominant role of hydrogen in A30 lies in its local plastic enhancement influence on coarse ferrite, which is the efficient diffusion path for hydrogen, and that in A70 consists in its decohesion effect on ferrite/austenite interfaces, due to the inherited hydrogen of the fresh martensite at interfaces. This work provides a vital insight for microstructural design to improve hydrogen embrittlement resistance for medium Mn steels. • The initial GBs characteristics play a decisive role in the annealed microstructure. • The 3-dimensional channels regulate the structure-induced hydrogen redistribution. • Hydrogen redistribution controls HE behaviours and types of HE mechanisms. • HE mechanisms, i.e. HELP and HEDE, are clarified at multiscale. [ABSTRACT FROM AUTHOR]