Determination of fracture toughness of AZ31 Mg alloy using the cohesive finite element method

The objective of this study is to develop a micromechanical approach for determining the fracture toughness. A phase-field model for grain growth is employed to generate microstructures with varying attributes and the cohesive finite element method is employed to quantify the interaction between a propagating crack and microstructures of an AZ31 Mg alloy. Simulations show that fracture toughness increases as the average grain size decreases and that the local crack tip environment significantly affects the fracture behavior. Dramatically different dependences of fracture toughness on overall strain rate are seen when two different types of cohesive laws are employed.

► An approach based on CFEM and phase-field model is developed to evaluate KIC.
► KIC increases as average grain size decreases for Mg alloy.
► Local crack tip environment significantly affects fracture behavior.
► Both nature of critical CTOD and cohesive law can dramatically alter trend of KIC.