Ferritic microstructure
Ferritic structure is a soft, ductile, and magnetic phase of iron with a body-centered cubic crystal structure. It has low carbon solubility and governs the deformation behavior of unalloyed structural steels.
Physico-Chemical Mechanism of Action
Ferritic structure consists of a body-centered cubic crystal lattice (γ-phase). It has low carbon solubility and forms at low temperatures with slow cooling. The atoms are well arranged, leading to soft and ductile properties.
Metallurgical Relevance & Risks in Welding
Ferritic structure is typical for unalloyed steels and has good formability. However, if cooling is too fast, martensite formation can occur, increasing hardness and reducing ductility. This can lead to cracking and hot cracking.
Workshop Practice & Action Guidelines
To maintain ferritic structure when welding, cool the weld slowly (t8/5 > 25 s). Use appropriate shielding gas or insulation methods. With high carbon content, the structure can change to martensite, which happens with too fast cooling.