PhD Dissertation: Ragıp Orkun Seçer, PHASE-FIELD SIMULATION OF GRAIN EVOLUTION AS A COMPONENT OF DIGITAL TWIN FOR 3D METAL PRINTING, Date & Time: 20 July, 2026 – 2:00 PM, Place: FENS L065
PHASE-FIELD SIMULATION OF GRAIN EVOLUTION AS A COMPONENT OF DIGITAL TWIN FOR 3D METAL PRINTING
Ragıp Orkun Seçer
Manufacturing Engineering, PhD Dissertation, 2026
Thesis Jury
Prof. Mehmet Yıldız (Thesis Advisor)
Prof Syamak Hossein Nedjad (Thesis Co-advisor)
Prof Burç Mısırlıoğlu
Prof Erhan Budak
Assoc. Prof. Nima Haghdadi
Assoc. Prof. Hatice Sinem Şaş Çaycı
Date & Time: 20th July, 2026 – 2:00 PM
Place: FENS L065
Zoom Link: https://sabanciuniv.
Keywords : Additive Manufacturing, Phase-Field Modeling, Orientation-Field Method, Phase-Field Crystal, Microstructure Evolution
Abstract
Metal Additive Manufacturing (MAM) enables the production of complex, high-value metallic components through localized melting and resolidification driven by a scanning energy source. The resulting steep thermal gradients and rapid cooling generate highly anisotropic microstructures, most notably elongated columnar grains that inherit their orientation from previously solidified material and curve according to melt-pool geometry. Because grain morphology and texture directly govern mechanical properties, residual stress, and the qualification of safety-critical components, there is a growing need for predictive, physics-based models that link process parameters to microstructural outcomes. This dissertation develops two complementary frameworks toward this goal. First, a coupled phase-field and orientation-field model, known as the WKLC formulation, which represents an entire polycrystal with a single orientation field, is extended to additive manufacturing by introducing a moving heat source and a temperature-dependent orientation mobility that suppresses unphysical grain coarsening in the cold solid. In both two and three dimensions, the model reproduces epitaxial regrowth, competitive growth, and curved columnar grains, and predicts microstructural changes under reverse scanning and repeated surface remelting; the computed pole figures show qualitative agreement with EBSD measurements of single-track 316L stainless steel. Second, a non-isothermal phase-field-crystal model couples atomic-scale density evolution to a moving thermal field, resolving epitaxial regrowth, serrated grain boundaries, subgrain misorientation, and elastic lattice bending, and revealing a kinetic supercooling that grows with scan velocity. Together, these frameworks connect process parameters to grain morphology, texture, and defect structure, advancing the microstructure-aware digital twins required for the qualification and control of additively manufactured metals.