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Major advantage of micromechanical models for prediction of two basictypes of fracture, ductile fracture and cleavage fracture, should be non-dependence ofmodel parameters on geometry. In this way it is possible to determine fracture parameterson limited quantity of material using small specimens. In this paper, ductile fracture ofstructural steel has been analysed on specimens without initial crack and precrackedspecimens. A part of investigation was carried out through participation in NumericalRound Robin on Micro-Mechanical Models organised by European Structural IntegritySociety (ESIS). Additional quantitative metallurgical analysis was made in order todetermine volume fraction and mean free path of non-metallic inclusions in tested steel.Finite element calculations on different geometries were performed.Based on non-coupled (the Rice-Tracey model) and coupled (modified Gurson model)micromechanical approaches, crack initiation and onset of growth on tensile specimenshave been analysed. Simplified procedure for determination of critical values of modelparameters corresponding to ductile fracture initiation was proposed. Good transferabilityof parameters determined on simple geometry to the analysis of behaviour of precrackedgeometry in ductile fracture condition was established. End goal of investigations that arein progress is analysis of actual precracked structure by applying micromechanicalapproach and simplified method of determination of ductile fracture parameters.