Lath martensite
Lath martensite is a fine, highly dislocated microstructure formed during rapid cooling of steels with low to medium carbon content. It consists of parallel-arranged martensite laths.
Physical-Chemical Mechanism of Action
During rapid cooling of steels with low to medium carbon content (approx. 0.2% to 0.5%), lath martensite forms. This process involves the rapid formation of martensite laths in parallel directions.
Metallurgical Relevance & Risks in Welding
Lath martensite increases the hardness and strength of the steel, making it well suited for high loads. However, it can lead to hot cracking if cooling is too rapid. This can especially occur with thick components or with uneven thermal conductivity of the workpiece.
Workshop Practice & Instructions
To avoid lath martensite, cooling should be controlled and slow. This can be achieved by using cooling water or special coolants. For steels with low carbon content, a cooling time of at least 10 seconds per cm of thickness is recommended.