Effect of microstructure on hydrogen trapping behavior and hydrogen embrittlement sensitivity of medium manganese steel

Purpose The purpose of this paper is to investigate the effect of microstructure on the hydrogen trapping behavior and hydrogen embrittlement sensitivity of medium manganese steels. Design/methodology/approach In this paper, the effect of microstructure on the hydrogen trapping and hydrogen embrittlement sensitivity of medium manganese steels has been investigated using a combination of microstructure observation, electrochemical hydrogen penetration experiments, thermal desorption spectroscopy (TDS) analysis and slow strain rate tensile experiments. Findings TDS and microstructure analyses reveal that in samples annealed at 640°C and 660°C, the primary hydrogen traps are dislocations, grain boundaries and carbides. The retained austenite (RA) hydrogen trap begins to appear after annealing at 680°C. At the critical annealing temperature of 700°C, the carbides have completely dissolved, resulting in almost no hydrogen trapping related to carbides. Moreover, samples annealed at higher temperatures exhibit a greater sensitivity to hydrogen embrittlement, which can be attributed partly to the irreversible hydrogen trapping caused by the dissolution of carbides and partly to the formation of strain martensite during deformation of the excessive RA. Originality/value RA content is closely related to hydrogen capture and hydrogen embrittlement susceptibility in medium manganese steels.