EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Deterioration in mechanical properties of metals and alloys due to hydrogen is known as hydrogen embrittlement, which leads to the catastrophic failure of structural components. The phenomenon of hydrogen embrittlement has been known for decades [1] and several mechanisms have been proposed to cause the hydrogen embrittlement such as hydrogen enhanced localized plasticity (HELP), hydrogen enhanced decohesion (HEDE) and stress induced hydride formation [2].

High manganese twinning induced plasticity (TWIP) steels are used for load bearing applications. It has been reported that TWIP steels are susceptible to the hydrogen embrittlement [3,4]. We studied the hydrogen embrittlement phenomenon in a cold rolled and recrystallized model TWIP steel with a composition of Fe 28Mn 0.3C (Wt. %). We performed the tensile tests on an uncharged and on electrolytically charged TWIP steel samples. The microstructural evolution during the tensile testing was examined by correlative microscopy that involves electron backscatter diffraction (EBSD) and electron channelling contrast imaging (ECCI) techniques. We observed the formation of dislocation cells, stacking faults, ɛ-martensite at different stages of tensile deformation in the hydrogen pre-charged samples, which is attributed to the influence of hydrogen on the stacking fault energy in TWIP steels.

References:
1. W.H. Johnson, On Some Remarkable Changes Produced in Iron and Steel by the Action of Hydrogen and Acids, Proc. R. Soc. London. 23 (1874) 168–179
2. P. Sofronis, I.M. Robertson, Viable mechanisms of hydrogen embrittlement - A review, AIP Conf. Proc. 837 (2006) 64–70. doi:10.1063/1.2213060.
3. M. Koyama, E. Akiyama, Y.K. Lee, D. Raabe, K. Tsuzaki, Overview of hydrogen embrittlement in high-Mn steels, Int. J. Hydrogen Energy. 42 (2017) 12706–12723.
4. An D, Krieger W, Zaefferer S. Unravelling the effect of hydrogen on microstructure evolution under low-cycle fatigue in a high-manganese austenitic TWIP steel. Int J Plast 2019.