Effect of hydrogen charging on anisotropic tensile deformation behavior of high strength steel plate

Xu, P. G.   ; Ishijima, Yasuhiro ; Qiu, H.*; Morooka, Satoshi  ; Gong, W.*; Harjo, S.   

Hydrogen-induced ductility loss or hydrogen embrittlement is related to the diffusional entrance of environmental hydrogen into ultrahigh strength steel materials. Neutron diffraction as a powerful nondestructive method has been developed well for monitoring the elastoplastic deformation and the crystallographic texture evolution. However, considering the tiny amount of diffusive hydrogen on crystal structure of steel materials, the monitoring using neutron diffraction is thought as a challenging research. Neutron diffraction during tensile deformation of cylinder samples prepared from a 12mm-thick high strength steel plate with and without hydrogen charging was carried out in situ, and the grain orientation rotations were discussed through the relative change of normalized integration intensity of individual diffraction peaks. The anisotropy of elastoplastic deformation behaviors of high strength steel plate and the effect of hydrogen charging on total elongation and reduction in the area has been confirmed. 110-fiber preferred orientation becomes stronger during uniaxial tensile deformation of samples with and without hydrogen charging; the complex multiaxial stress field during local necking deformation induces more evident weakening of final 110-fiber preferred orientation in the non-hydrogen steel than the hydrogen charged steel, suggesting that neutron diffraction is suitable for monitoring the plastic deformation of hydrogen-charged high strength steel.