Influence of hydrogen on the S–N fatigue of DP1180 advanced high-strength steel

We studied the load-controlled fatigue behaviour (at a stress ratio R = 0.1, 1 Hz, using smooth flat-sheet specimens) in air and with hydrogen (electrochemically charged at a current density of 16 mA cm−2 in 0.1 M NaOH) for a 1180 MPa dual-phase advanced high-strength steel. There was no significant difference between the fatigue lives with hydrogen and in air, even though there was a clear influence of hydrogen on the fatigue fractography. The hydrogen diffusion coefficient (0.8 ×10−6 cm2 s−1) and a hydrogen content of 1.0 µg g−1 were evaluated using hydrogen permeation experiments. A rougher surface produced a shorter fatigue life.