Abstract
	The physical metallurgy conditions of intragranular nucleation of acicular ferrite (AF) in low-carbon steel are analysed. The nucleation of AF laths is induced at fine dispersed particles of Ti-oxides (Ti2O3) detected in Ti-bearing steels. In given steel category the particles of considered inclusions are adhered with MnS and TiN, which contribute to the nucleation process of AF. The increase of chemical free enthalpy due to Mn-depleted zone formed in austenite after MnS precipitation and decrease in interfacial energy between TiN and AF particles are taken into consideration. The interfacial affect results from high level of lattice registry between AF and TiN. The Mn-depleted zone can be also formed after preferential diffusion of Mn-atoms into considered Ti inclusion category what is connected with high concentration of cation vacancies in these particles. Besides Mn-depletion mechanisms leading to the preferential austenite decomposition in critical zone of austenitic matrix, the TiN particles characterised with low interfacial energy of AF laths can contribute to their nucleation process of this phase.