Digital image correlation for the characterization of fatigue damage evolution in brazed steel joints

In this work, the fatigue behavior of brazed steel joints in different heat treatments and geometries was investigated and compared with the behavior of the steel substrate. Cyclic loading experiments were performed on a servo-hydraulic testing facility at R = 0.1. The results showed that brazed round specimens exhibit higher plastic strains and lower fatigue lifetimes at similar loading amplitudes when compared with their substrate material. Furthermore, the S,N-curves show that heat treatments which are performed after brazing significantly influence the fatigue lifetime and the defect tolerance of the brazed specimens. To investigate the local effects of the thin braze layer, digital image correlations (DIC) were performed with a high speed camera. The results show the complex interactions of a braze layer with the surrounding material and lead to a better understanding of the fatigue behavior of brazed steel joints. (C) 2014 Published by Elsevier Ltd.