Fuzzy Model-based Charpy Impact Toughness Assessment for Ship Steels

The present research aims at linking steel composition and microstructure to a prediction of Charpy impact properties of ship structural steel, including Charpy impact energy, transition temperature (ITT) and fracture appearance (brittleness). In this paper, adaptive fuzzy modelling techniques were applied to develop generic models for the prediction of Charpy impact properties of Grade A and AH36 ship steels. Using the proposed fuzzy modelling approach, the rule-based fuzzy prediction models, which involved chemical composition, grain size, tensile strength and Charpy impact energy, were generated and optimised automatically from numerical data. The investigation of the relationship between Charpy impact energy and fracture surface characteristics is also presented in the paper. Numerical analysis shows that using the obtained fuzzy models we are able to predict Charpy toughness for given steel compositions and microstructures, and also reveal useful qualitative information linking composition-microstructure to Charpy impact properties.