Experimental and ductile fracture model study of single-groove welded joints under monotonic loading

•19 tensile and fracture tests of steel welded specimens under monotonic loading are presented.•Three-stage and two-parameter ductile fracture model is proposed and its application is validated.•Effect of notch position on ductile fracture behavior of HAZ specimens is investigated.•Mesh size dependency of V- and U-notch specimens is studied.•The values of two parameters for base metal, weld metal and HAZ are determined.

Tests and finite element (FE) analyses of smooth flat bar, U-notch and V-notch specimens are presented to demonstrate the application and validation of proposed three-stage and two-parameter ductile fracture model for evaluating the ductile crack initiation, propagation and final failure in steel welded joints under monotonic loading. Modeling concepts and procedures for characterizing the material parameters of ductile fracture model using smooth flat bar and U-notch tests are described. Accuracy of the model is validated through a series of tensile tests of U-notch, V-notch and welded smooth flat bar specimens. Three types of materials used in welded structures including base metal, weld metal and HAZ are investigated. Furthermore, the effect of notch position on ductile fracture behavior of HAZ specimens and the effect of mesh size on ductile fracture behavior of U-notch and V-notch specimens are studied. Detailed finite element analyses that employ the ductile fracture model are shown to predict ductile fracture behavior with good accuracy across the specimen geometries and material types in terms of ductile crack initiation point, ultimate load point and load–displacement curve.