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

Abstract

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.