Locally restricted microcrack
A microscopic separation crack in the crystal structure that acts as a cause of fatigue fractures under repeated loading.
Physicochemical Mechanism of Action
A microcrack is a very small crack at the microscopic level in the metal. It arises from mechanical stresses or chemical reactions and can serve as a starting point for further material degradation.
Metallurgical Relevance & Welding Risks
Microcracks can form during the welding process, especially when the metal is subjected to high pressure or uneven stresses. They act as initiation points for fatigue fractures that can propagate under cyclic loading (like thermal cycling). This can lead to premature weld failure.
Workshop Practice & Instructions
To minimize microcracks, it is important to ensure a clean weld pool and proper heat input. Use metals with low susceptibility to microcracking for high-stress applications and ensure careful cooling to stabilize the microstructure.