Material Parameters in Void Growth Model for G20Mn5QT Cast Steel: Calibration and Verification

Abstract

Micromechanical fracture models, void growth model (VGM) and stress-modified critical strain (SMCS) model, can predict the ductile fracture of structural steels by investigating the growth of microvoids existing inside materials. Based on test results on smooth notched tensile specimens, in this paper, material parameters in the VGM and the SMCS model were calibrated for G20Mn5QT cast steel. A monotonic tension test on a double-hole plate specimen was carried out to verify the calibrated material parameters. Predictions for the ductile fracture initiation of the double-hole plate specimen by the two micromechanical fracture models agreed well with test results. The fracture propagation of the double-hole plate specimen during the whole loading process was then simulated by deleting fractured elements identified by the VGM. The load-deformation curve and fracture propagation process obtained by numerical simulation were consistent with the test results, which further verified the calibrated material parameters and the approach to simulating fracture propagation based on the VGM.