Cleavage Fracture Facet
Cleavage facets are smooth, crystallographic fracture surfaces that occur along specific planes at low temperatures or high loading rates. They lead to brittle material and increase the risk of cracking.
Physical-Chemical Mechanism of Action
Cleavage fracture facets occur due to brittle separation along crystallographic planes. This happens at low temperatures or high loading rates, where the material is no longer ductile and instead separates in a brittle manner.
Metallurgical Relevance & Risks in Welding
Cleavage fracture facets increase susceptibility to cracks and fractures. They make the material softer and less tough, leading to lower strength. This can be a significant risk, especially in stiff materials like steel.
Workshop Practice & Instructions
To avoid cleavage fracture facets, it's important to control the weld and temper the material before welding. In high stress applications, choose low temperatures and slow cooling rates. The cooling time should be at least 25 seconds to achieve sufficient grain refinement.