Effect of loading mode on blistering in iron submitted to plastic prestrain before hydrogen cathodic charging

Tensile tests and simple shear tests have been performed on Armco iron sheets before hydrogen cathodic charging, in order to study the effect of loading mode on blistering of plastically prestrained samples. The experimental results from surfometry and image analysis show the decrease of the blisters size with prestrain increase, and quantitative differences between tensile or shear prestrain are exhibited. Phenomenological modeling of blister initiation is proposed, based on void expansion increase under internal pressure, and considering both plastic strain and pores as traps during hydrogen transport. Finite element simulations of material expansion due to hydrogen induced void growth lead to qualitative agreement with experimental tendencies. •Blisters on iron after cathodic charging depend on plastic prestrain and loading mode.•Surfometry and SEM exhibit blister size decrease with increasing plastic prestrain.•Blistering initiation by void expansion under internal pressure is modeled with FE.•FE simulations exhibit the differences between tensile and shear loading mode.