Interactions of stress corrosion cracks in cold drawn pearlitic steel wires: An X-ray micro-computed tomography study

Highlights: • Micro-CT mapped the complex 3D structures of stress corrosion cracks and their interactions. • Registered 2D OM and SEM images were directly compared with the corresponding slice from the 3D micro-CT image. • The attributes of each subcritical crack were computed from the micro-CT image and plotted to establish their intercorrelations. • Most of the internal surfaces exposed to the corrosive environment was provided by crack branching. • A combination of 3D micro-CT imaging and high-resolution 2D techniques enables a comprehensive characterization of SCC. X-ray micro-computed tomography (micro-CT) was used for analysis of stress corrosion cracking (SCC) of cold drawn pearlitic steel wires from a cable bolt from an underground coal mine. The results were compared to those obtained from magnetic particle inspection (MPI) of the wire surface and optical microscopy (OM) and scanning electron microscopy (SEM) examination of sections through the wires. The high-resolution two-dimensional (2D) OM and SEM images were registered into the micro-CT image to allow direct comparison with the corresponding slice from the three-dimensional (3D) micro-CT image. Subsequently, the micro-CT image was processed to segment the cracks in the steel body and the attributes of each crack, i.e. the surface area, surface exposure, and maximum radial and longitudinal penetration depths, were calculated and plotted to determine their intercorrelation. It was found that MPI and micro-CT had a similar ability in revealing surface cracks. The 2D techniques provided high-resolution information but unlike micro-CT they were unable to map the complex 3D structures of the cracks and their interactions.