No mechanical stress

Uniform corrosion

Uniform corrosion refers to the corrosion that occurs on all or most of the metal surfaces with the same corrosion rate.

Localized corrosion

On the contrary, local corrosion refers to the corrosion that occurs in various parts of the metal surface. The root cause is the formation of corrosion products with different solubility, resulting in local different corrosion loads (temperature, concentration, flow rate, etc.).

pitting

Pitting corrosion is a kind of material corrosion limited by electrochemistry, which leads to the formation of pitting holes. The root cause lies in the existence of corrosion factors, mainly chlorides. Pitting corrosion is particularly serious on stainless steel and aluminum alloys.

Crevice corrosion

Crevice corrosion is a narrow gap between similar metals or between metals and nonmetals. Corrosion is caused by the increase of chlorides or the decrease of oxygen that forms the oxide layer.

Contact corrosion

Contact corrosion (galvanic corrosion) is caused by corrosion factors due to different corrosion electrode potentials between metals. During this period, the dissolution rate of metal (anode) with low electrode potential is accelerated, and the metal with high electrode potential becomes the cathode reaction surface. The corrosion rate is determined by the difference of corrosion electrode potential and the ratio of two reaction surfaces. When the potential difference of corrosion electrode is large, it is extremely unfavorable if the anode area is small and the cathode area is large.