Optical second harmonic generation characterization of tensile deformation in steel

Abstract Tensile deformation in materials such as aluminum and steel changes the structure in ways that can lead to loss of mechanical properties and even catastrophic failure. Based on prior work on 2024 aluminum ( https://doi.org/10.1088/1361-6501/abe668 ), optical second harmonic generation (SHG) was applied to 410 stainless steel samples. The prior work on aluminum showed a correlation between the change in SHG response and the dislocation density, as measured by electron back scatter diffraction (EBSD), following tensile deformation. Similar EBSD and SHG measurements were performed on 410 stainless steel. When spatially averaged, a similar trend was observed of decreasing SHG response with increased deformation. However, the steel samples showed a greater spatial sensitivity than had been seen with aluminum, with measurements taken 1 or 2 mm away from the center showing a different SHG response than the center position. This spatial sensitivity serves as motivation to develop SHG imaging of larger areas of the sample to better determine how the damage localizes in response to deformation. SHG imaging could thus be a powerful addition to the suite of techniques used for nondestructive evaluation of structural materials.