Fatigue Crack Growth
Fatigue crack growth is the process where a crack slowly grows under repeated loading. The Paris law describes the crack growth rate as a function of the stress intensity factor.
Physico-chemical mechanism of action
Under cyclic loading, such as alternating heating or vibrations, microscopic cracks form in the material. These cracks slowly grow due to repeated stress applications. The Paris law gives a mathematical description of this process and shows that the crack growth rate is proportional to the square of the stress field.
Metallurgical relevance & risks in welding
Fatigue cracks can lead to critical safety problems, especially in machine components under high stress. A crack that slowly grows can eventually cause fracture and destroy the material. This is particularly dangerous in high-load applications such as mechanical engineering or the aerospace industry.
Workshop practice & action instructions
To avoid fatigue crack growth, the stress situations must be analyzed and optimized. This can be achieved by proper material selection, careful manufacturing processes, and regular inspection of components. In welding, it is important that the weld is strong enough to withstand cyclic loads. This can be ensured by adequate heat input and proper cooling.