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A generic study of the relationship between fracture toughness and microstructureof ductile metals has been performed using a continuum damage model in a 2D small scaleyielding finite element setting. The damage model is an enhanced Gurson modelincorporating void shape effects and a micromechanical law for void coalescence. Emphasisis placed on cracking initiation. The results agree very well with recent calculations byTvergaard and Hutchinson based on a finite element analysis which explicitly incorporates arow of voids in the discretization. The effect of the flow properties and of the void shape onthe fracture toughness is discussed. Transition between a void by void growth and a multiplevoid interaction is analysed. The paper also addresses the difference between the fracturetoughness at true cracking initiation and the fracture toughness defined in an engineeringsense, i.e. after a given amount of crack propagation.