Corrosion fatigue 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). 

The description shall include materials and dimensions and shall be supported by drawings. The effects of corrosion, fatigue, neutron doses, etc., on the lifetime of mechanical components that are related to safety shall be discussed. 

Ill-103. Reactivity control system, reactor shutdown system The function of the mechanical and electrical design shall be described. The description shall include the materials and dimensions and shall be supported by drawings. The reactivity control mechanisms and their instrumentation, such as their position or status (coupled/decoupled), should be presented, together with their insertion time and interlocks. The effects of corrosion, fatigue, neutron doses, etc., on the lifetime of the mechanical and electrical components shall also be discussed. The safety related design parameters should be presented, such as ... 

Again, wear is the removal of material. The idea that friction causes wear and therefore, low friction means low wear, is a common mistake. Brief descriptions of five types of wear abrasive, adhesive, fatigue, chemical or corrosive, and fretting — may be found in Reference 2 as well as in other references in this article. Next, it maybe useful to consider some of the major concepts of lubrication. 

---