Studying hydrogen embrittlement in nano-twinned polycrystalline fe-12.5mn-1.2c austenitic steel

Abstract

Embedding austenitic structures with nano-twinned grains is a promising technique to enhance its strength and ductility, nano twins can be introduced via thermo-mechanical processing or via electro-deposition. In the current study, ternary Fe-Mn-C austenitic steel was cold rolled then subjected to flash annealing to keep some nano twins within the matrix. It was found that, the nano twinned condition showed better resistance to Hydrogen embrittlement (HE) than the as received state. In addition, notched samples charged with hydrogen were tensile tested to investigate the contribution of the nano-twinned grains in impeding cracks initiation/propagation, it was concluded that the prior twins distributed homogeneously the internal stresses inside the austenitic grains during the plastic deformation, which prevented cracks propagation at earlier strain level, and this delayed time till fracture happened.