Influence of the mode of deformation and hydrogen charging on mechanical properties of 40X steel with surface nanostructure

The influence of the unidirectional and multidirectional mode of severe plastic deformation generated by mechano-pulse treatment on the formation of tensile mechanical properties of the 40X steel with surface nanostructure with and without electrolytic hydrogen charging was studied. Due to such treatment, the yield strength of the obtained material was improved almost 2 times. However, the characteristics of plasticity changed ambiguously: the elongation decreased in comparison with the as-received state, and the reduction of area after the multidirectional deformation increased. The increment of the modulus of elasticity and formation of the equiaxed nanocrystalline structure, which enables the transition of the severe plastic deformation to the advanced stage when plastic shear is suppressed and only plastic rotation occurs, was considered. The multidirectional deformation generally increased strength characteristics and retained the area reduction, as in the steel that was received after hydrogen charging.