Using Spatial Statistical Analysis of Taylor Factors to Characterize Material Susceptibility to Intergranular Stress Corrosion Cracking

摘要

Studies have shown that variations in Taylor factor from one grain orientation to the next can help predict failure in materials. The differences in Taylor factor between neighbouring grains increases the likelihood of dislocation pile-ups at the grain boundaries. Sharp dislocation gradients resulting from large contrasts in Taylor factors lead to the formation of voids, which act as a precursor to future intergranular stress corrosion cracking. In this study, the spatial variability in Taylor factor is correlated with failure potential using spatial statistical analysis. The spatial correlation of Taylor factors is quantified through variogram analysis, which describes the dissimilarity in Taylor factor across the sample as a function of lag distance. The methodology is applied to the analysis of cracked and un-cracked samples of carbon steel piping. The Taylor factor mapping was obtained through Orientation Imaging Microscopy (OIM). The results of the study demonstrate how the variogram provides a quantifiable measure of variability that is consistent across samples at different scales, and hence is an effective method for identifying material susceptibility to intergranular cracking.