Explanation

The process of micro or macro cracks in materials growing under external force or environmental action (or combined action). The propagation of micro cracks will lead to the nucleation of macro cracks. The early stage of macro crack propagation is the continuous growth of the crack (called steady state growth). When the crack grows to the critical size, the continuous growth will lead to the fracture of the sample or component (called unstable growth). Cracks can be divided into cracks formed during loading in inert medium, fatigue cracks, creep cracks, stress corrosion and hydrogen induced cracks. The propagation laws and mechanisms of these cracks are different and should be studied separately. Under the condition of plane strain, 2% of crack propagation is taken as the critical condition of unstable propagation. crack propagation rate is an important parameter in fatigue, stress corrosion and hydrogen induced cracking.

Classification