Lamellar pearlite formation
Lamellar pearlite formation is a fine layered composite structure of ferrite and cementite, produced by cooperative diffusion during the transformation process. It improves the hardness and toughness of steel.
Physical-Chemical Mechanism of Action
Lamellar pearlite formation occurs when the carbon content in the molten pool is between 0.6% and 1.2%. During cooling, carbon atoms diffuse from the copper matrix into the ferrite phase. This leads to a fine layered composite structure with ferrite and cementite layers.
Metallurgical Relevance & Welding Risks
Pearlite formation increases the hardness and toughness of the steel, making it suitable for hard applications. However, too much pearlite (above 20%) can lead to excessive hardness, making the material prone to cracking. Additionally, it can reduce formability.
Workshop Practice & Action Guidelines
To achieve optimal pearlite formation, keep the carbon content in the molten pool between 0.6% and 1.2%. Control the cooling steps to maintain the fine layered structure. Rapid cooling can lead to martensite formation, while too slow cooling produces too much ferrite.