Hydrogen causes intergranular brittle fracture in steels. It segregates to the grain boundaries and weakens them. This can be avoided by annealing the steel at 200 degrees Celsius for 30 minutes, which allows the hydrogen to leave the grain boundaries.
Apart from the hydrogen embitterment the shape of crack would affect the activation of the three fracture modes known as mode I, II and III. Therefore the geometry of the cracks in the grain boundaries is a controversial issue which can be detected by characterization of the grain orientations in vicinity of the crack.