Corrosion Fatigue Fracture

A fracture of a metal component caused by the combined action of cyclic stress and a corrosive medium is called corrosion fatigue fracture.

Compared with ordinary fatigue fracture (caused only by cyclic stress), a corrosive environment weakens the material through chemical or electrochemical reactions, promoting the initiation and propagation of cracks;

1. Characteristics of Corrosion Fatigue

a. Synergistic Effect: The interaction between the corrosive medium (such as saltwater or acidic environment) and mechanical stress reduces the fatigue limit of the material. Fracture may occur even when the stress is below the normal fatigue limit.

b. Crack Initiation: Corrosion leads to surface defects (such as pitting or intergranular corrosion), which become the crack initiation points where stress concentrates.

c. Crack Propagation: The corrosive medium penetrates the crack tip, accelerating its propagation through mechanisms such as dissolution and hydrogen embrittlement. The fracture surface may exhibit brittle features or corrosion products.

2. Fracture Surface Characteristics

Observing the fracture morphology with a scanning electron microscope (SEM) shows both corrosion features (such as pits and secondary cracks) and fatigue striations.