Multiscale 3D characterization of discontinuities in underwater wet welds

Underwater wet welding is performed in direct contact with other, with high cooling rates and gas metal reactions that lead to the formation of pores, cracks and inclusions in the weld metal. These discontinuities appear in a wide range of sizes, shapes and orientations, and require 3D techniques for complete characterization. Lab scale X-ray MicroCT was used to analyze pores and cracks, while synchrotron MicroCT and FIB/SEM were used to characterize inclusions. Specific image analysis sequences were developed to deal with different types of noise, segment the discontinuities, eliminate spurious features, and measure 3D parameters. The relevant objects were rendered in 3D, confirming the expected size and orientation characteristics. Whenever possible, results from different scales and techniques were compared. •Discontinuities in wet underwater welds were analyzed 3D imaging techniques.•Pores/cracks imaged with MicroCT; inclusions with synchrotron MicroCT and FIB/SEM•3D IA routines developed to filter, segment and measure discontinuities•3D image rendering confirmed size, shape and orientation of the discontinuities•Results from different scales and techniques were compared.