• **Crevice corrosion**

Crevice corrosion is a localized type of corrosion and is formed inside gaps or crevices on the surface of the metal. This type of corrosion can also affect the connected pieces to the metal substrate such as another welded metal or even metal attached to non-metal objects. The filling of crevices by corrosive agents, such as water, humidity, or pollutants, causes the rate of this type of corrosion to increase and eventually leads to the failure of the substrate [10]. **Figure 4** depicts the crevice corrosion in metals.

**Figure 4.** *The crevice corrosion in metals [10].*

 **Figure 5.**  *The pitting corrosion in metals [ 11 ].* 

 **Figure 6.**  *The erosion-corrosion in metals [ 12 ].* 
