Simulation Charpy impact energy of functionally graded steels by modified stress–strain curve through mechanism-based strain gradient plasticity theory

In the present work, Charpy impact energy of functionally graded steels produced by electroslag remelting composed of graded ferritic or austenitic layers in both crack divider and crack arrester configurations has been modeled by finite element method. The yield stress of each layer was related to the density of the statistically stored dislocations of that layer and assuming by Holloman relation for the corresponding stress–strain curves, tensile strengths of the constituent layers were determined via numerical method. By using load–displacement curves acquired from instrumented Charpy impact tests on primary specimens, the obtained stress–strain curves from uniaxial tensile tests were modified. The data used for each layer in finite element modeling were predicted modified stress–strain curves obtained from strain gradient plasticity theory. A relatively good agreement between experimental results and those obtained from simulation was observed.