The relationship between microstructures and anisotropic constitutive behaviors in wire-arc directed energy deposition

To reveal the internal relationship between microstructures and anisotropic mechanical properties in wire-arc directed energy deposition (DED), a new integrated model for process-microstructure-property relationship is proposed with experimental design for validation. It reveals that the grain boundary effect leads to the higher mechanical strength along scanning direction in comparison with building direction due to the smaller mean free path. The mechanical strength is decreased along the building direction. The yield strength in the scanning direction is decreased from 1036.54 MPa in 5th layer to 949.57 MPa in 25th layer. The change in mechanical properties under thermal accumulation is attributed to the reduced contributions from dislocation interactions and grain boundaries. The yield strength is decreased with the increase of temperature. The flow softening can be found in stress–strain curve after the initial hardening at 600 °C-800 °C due to the formed grain globularization at high temperatures.