Structural integrity of the deposit-substrate interface of wire + arc additively manufactured steel components

Remanufacturing of damaged parts can contribute to a more sustainable economy by reducing energy and materials consumption. For the dimensional restoration and structural repair of steel components, Wire + Arc Additive Manufacturing (WAAM) can be applied. Due to the high cyclical heat input during the WAAM process, a gradient in microstructure and mechanical properties will arise at the deposit-substrate interface. Methodologies are under development to investigate this heterogeneity in mechanical properties through sub-size quasi-static tensile tests and Compact Tension (CT) fatigue testing with extensive instrumentation. During tensile testing of specimens extracted parallel to the deposit-substrate interface, a periodic deformation pattern is observed in the strain field obtained through Digital Image Correlation (DIC). Surface height measurements of the failed specimens show that this pattern is related to the waviness of the interface due to the deposition of adjacent weld beads. CT specimens have been extracted with notches at different locations relative to the interface in order to investigate the fatigue crack growth rate, as well as possible crack path deviation.