HIC – HYDROGEN INDUCED CORROSION

The defects are caused by a process based on the diffusion of atomic hydrogen that is trapped e.g. on the surface of rolled inclusions. Thus, the atomic hydrogen creates gas H2 that leads to blisters around the inclusions. The atomic hydrogen also increases tendency of steel to localize plastic deformations into shear bands, which in turn results in tearing of the bridges between the blisters in 45° angle due to tension in the material. HIC – Hydrogen Induced Corrosion appears, and stress-oriented cracking between the bridges (SOHIC).

The suitable testing method is UT PA using manipulator, where complex picture is compiled from individual records. Computer processing allows “cutting” of 3D model created from the recording.