Super duplex stainless steels (SDSS) are often used in corrosive environments, such as oil and gas industries, due to their good combination of strength (>450 MPa yield strength and >700 MPa ultimate tensile strength) and corrosion resistance (pitting resistance equivalent number – PREN > 40). Achieving the desired properties of SDSS, as balanced austenite/ferrite phase composition and minimal deleterious phases, is challenging during the arc-based direct energy deposition (arc-based DED) manufacturing process due to its complex thermal cycles [1]. This work aims to gain a comprehensive understanding of microstructure evolution (nucleation, grain growth, phase transformation, elemental segregation, and phase balance) in SDSS arc-based DED parts in the light of phase field simulations. The phase field model is based on thermodynamic-driven partial differential equations, which model is coupled to both mass and heat transport phenomena including release of latent heat of solidification [2,3]. A validation experiment has been carried out by optical microscopy, electron scanning microscopy, differential scanning calorimetry, and X-ray diffraction, showing that the simulation results are consistent with the experimental results. Simulation reveals insights into local equilibrium conditions about heterogeneous nucleation, cellular solidification mode, oriented grain growth, phase fraction during solidification, and elemental partitioning; therefore, enhancing the understanding of solidification and phase transformation of the SDSS during arc-based DED process.