Fatigue Crack Growth Rate of ADB610 Steel Welded Joints

The ADB610 steel was welded using shielded metal arc welding method, and the fatigue crack length (a) vs. fatigue life (N) curves was measured by using crack compliance method. Base on a-N curves, the fatigue crack propagation rates of each sample from base material (BM), heat affected zone (HAZ) and weld seam (WS) were calculated by fitting a polynomial to a strip of 7 data points and linear regression fitted with stress intensity factor range (ΔK). The formula based on Paris of (da/dN) and (ΔK) was obtained. The results show that the fatigue crack growth rate in BM was higher than that in HAZ and WS, and that in WS was the slowest during the early and middle stage of crack growth; during the last stage of crack growth the difference of fatigue crack growth rate in three regions was not significant.