(V) Numerical Simulations of Fracture Tests of Uncharged and Hydrogen-Charged Specimens of Laser Powder Bed Fusion Processed Type 304L Stainless Steels

Continuum modeling of fracture behavior is important for additively manufactured materials. Continuum finite element analyses are used to model crack extensions in fracture tests of uncharged and hydrogen-charged specimens of laser powder bed fusion processed type 304L stainless steels using the nodal release method and cohesive zone model. The maximum opening stresses ahead of crack tips and separation work rates as functions of the crack extension are first obtained by the nodal release method as references for the varying cohesive strength and cohesive energy. The load-displacement-crack extension relations are then obtained using the cohesive zone model with the varying cohesive parameters by fitting the experimental data for the uncharged and hydrogen-charged specimens. The computational load-displacement-crack extension relations obtained from the finite element analyses using the cohesive zone model with the varying cohesive parameters can fit very well with the experimental data.