Corrosion Fatigue Crack-Growth Characteristics of Several HY-100 Steel Weldments with Cathodic Protection

摘要

The corrosion fatigue crack-growth properties of several types of HY-100 steel weldments were studied, primarily in an environment of seawater with cathodic protection by zinc anode. Shielded metal-arc and gas metal-arc of both pulsed and spray-arc processes, and submerged-arc weldments were included. The fatigue crack growth tests were conducted using compact specimens removed from the weldments to confine the path of the growing crack in all weld metal. Constant amplitude, sinusoidal loads were applied at a frequency of 0.17 hertz with a load ratio (minimum-to-maximum) of 0.10. In general, fatigue crack growth in weldments was considerably slower than that in HY-100 plate under the same conditions of load and environment, where the applied potential accelerated crack-growth rate. The results showed minor differences among the weldments. It was suggested that the residual stress along the weld center line, the inhomogeneity of the weld metal with respect to the crack path, defects, and minor porosity all act to retard crack growth, especially at lower stress intensity levels. These factors tend to mask the environmental effects. However, weldments prepared with high heat input showed greater resistance to fatigue crack propagation than weldments prepared at low heat input.