Prediction of Charpy impact toughness of steel weld heat-affected zones by combined micromechanics and stochastic fracture model – Part II : Model validation by experiment

[Display omitted] •Prediction of Charpy impact toughness of steels, especially that of weld heat-affected zone (HAZ) is a difficult task.•Charpy impact test for a variety of steel weld HAZ samples was conducted to validate the computational model.•The proposed model can predict Charpy transition behavior from microstructural parameters only, with good accuracy. The present paper presents the results of Charpy impact testing for a variety of simulated heat-affected zone (HAZ) samples having different chemical compositions and thermal cycles. The target microstructure was coarse-grained and predominantly composed of upper bainite with martensite-austenite (MA) constituents. Microstructural parameters, including volume fractions of the MA and grain boundary (GB) ferrite and the statistical distributions of the MA particle thickness, lath width and GB ferrite thickness, were measured. All these data were fed into the computational model to predict the Charpy impact absorbed energy transition behavior, presented in Part I. The predicted results agreed well with the experimental results. The present model does not rely on data from multiple specimens, but the Charpy absorbed energy together with its scatter can be predicted from the microstructural parameters and tensile properties only.