Lenticular Martensite
Lenticular martensite is a lens-shaped microstructure with high carbon content, characterized by heavy twinning. It is very hard but brittle and leads to hot cracking.
Physical-Chemical Mechanism of Action
Lenticular martensite forms during rapid cooling of high-carbon weld seams from high temperatures. Rapid cooling prevents full transformation and results in a lens-shaped structure with many twin lines.
Metallurgical Relevance & Welding Risks
This microstructure is very hard, which improves its mechanical properties. However, it is also very brittle and leads to increased susceptibility to hot cracking. This can cause component failure and reduce the life of the weld joint.
Workshop Practice & Action Instructions
To avoid lenticular martensite, it is crucial to carefully control the cooling rate during welding. The cooling time should be long enough for the microstructure to fully transform. Recommended times are between 10 and 20 seconds for the cooling process.