Modeling fracture toughness of functionally graded steels in crack arrester configuration

By utilizing plain carbon and austenitic stainless steels with different thicknesses and arrangements as electrodes of electroslag remelting, functionally graded steels containing graded ferritic and austenitic regions together with bainite and martensite intermediate layers were produced. Fracture toughness of the functionally graded steels in crack arrester configuration has been demonstrated to depend on the position and sense of the graded region in which the crack is located. When a propagating crack experiences an upward gradient of fracture toughness, the fracture toughness of the composite is increased and vice versa. An analytical model has been presented for predicting fracture toughness of the composites. Also 3D numerical simulation by conducting finite element method has been presented. There is a good agreement between experimental results and those obtained by the analytical and numerical models.