Abstract
The corrosion fatigue crack growth behavior in the butt welded joints of low carbon steel has been studied and discussed in relation to the welding residual stress and corrosion deposits.
In air, the fatigue crack growth rate was scarcely influenced by the tensile residual stress, but the compressive residual stress reduced the fatigue crack growth rate. In seawater, the effect of compressive residual stress on the corrosion fatigue crack growth rate was less than that in air. When the stress ratio was increased, this effect was scarcely observed. However the occurrence of the wedging effect due to corrosion deposits was confirmed in seawater except the case of compressive residual stress at low stress ratio. When the crack closure occurred by the compressive residual stress in seawater, the corrosion deposits formed within fatigue cracks were fractured by contact with the closing crack planes, but they were formed again. Such an mechanism seemed to occur particularly in the compressive residual stress field. Thus, the corrosion fatigue crack growth rate in the compressive residual stress field was remarkably accelerated by the aggressive attack of seawater.
