Effect of a deposit-substrate interface on fatigue crack propagation in WAAM-deposited SS316L: XFEM modeling with orthotropic material properties

The extended finite element method (XFEM) is used to investigate the fatigue crack growth (FCG) behavior at the interface of the SS316L deposited with wire arc additive manufacturing (WAAM) on SS316 substrate. The study considers compact tension specimens with four notch locations along the interface of WAAM deposition and substrate to analyze the overall FCG behavior. Build direction cracks divert from their initial trajectory towards WAAM region due to the uneven material field at the crack tip. Even with mode-I loading, crack path deflection is driven by the uneven stress distribution at the crack tip, which is caused due to WAAM region having smaller elastic modulus in comparison to the substrate. The stress field near the crack front provides insights into the crack-kinking mechanism. Numerical predictions of FCG behavior align well with experimental observations.