Abstract
Fatigue crack propagation properties of welded joints were investigated for five types of steels, SB42, SM50B, SPV50, HT80 and SUS304. Propagation data for all materials were found to be coinciding with each other. This was due to the presence of tensile residual stress around the crack tip which made the crack surfaces to open. A total of 3, 335 data plots were used to fit a regression curve. For design purpose, it is advisable to adopt the fatigue crack propagation curve at 99.5% confidence limit. It is also shown that the proposed curve is applicable to random loadings.
