Corrosion fatigue cracking description

General description. In incomplete fusion, complete melting and fusion between the base metal and the weld metal or between individual weld beads does not occur (Fig. 15.8). Incomplete fusion that produces crevices or notches at surfaces can combine with environmental factors to induce corrosion fatigue (Chap. 10), stress-corrosion cracking (Chap. 9), or crevice corrosion (Chap. 2). See Fig. 15.9. 

Consequently, the parametric response of a material to corrosion fatigue loading may be quite complex, and the description of corrosion fatigue behavior must take into account not only the level of mechanical loading but also the load frequency and the shape of the cycles. Results should be expressed in terms of time related crack growth rate (dfl/dr) rather than the more frequently used cycle dependent crack growth rate (da/dn). 

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