شبيه‌سازي عددي ريزساختار انجمادي در فرايند ذوب بستر پودر با ليزر آلياژ دوتايي Fe-17wt%Cr به روش ميدان فاز

Laser powder bed fusion (LPBF) is one of the most complex metal additive manufacturing processes for predicting solidification microstructures, owing to its high cooling rates, steep thermal gradients, an‎d intricate interactions among heat transfer, fluid flow, an‎d solidification phenomena. In this study, a multiscale numerical framework is developed to predict the solidification microstructure of 316L stainless steel by directly transferring local solidification conditions from macroscale process simulations to a phase-field-based microscale model. The framework integrates a three-dimensional multiphysics finite-volume model for melt-pool dynamics with a phase-field model for rapid solidification of a Fe–17 wt.% Cr alloy. The results show that increasing the energy density from 104 to 208 J/mm³ increases the melt-pool depth-to-width ratio from 0.47 to 0.87, while decreasing the thermal gradient from 6.44 × 10⁶ to 3.40 × 10⁶ K/m an‎d the cooling rate from 6.44 × 10⁶ to 2.04 × 10⁶ K/s. As a result, the primary cell spacing increases from 3.6 to 5.5 μm, indicating a coarsening of the solidification microstructure. Under most processing conditions, cellular growth is found to prevail over columnar dendritic growth. Comparison with experimental measurements demonstrates that the phase-field model predicts the primary cell spacing with an average error of less than 10%. Furthermore, the effects of a double-beam scanning strategy an‎d different melting regimes, including conduction, transition, an‎d keyhole modes, on the thermal behavior an‎d solidification microstructure are investigated. The results reveal that both the scanning strategy an‎d melting regime can substantially influence the solidification mode, alloying-element segregation, an‎d stability of microstructural growth. Overall, the proposed multiscale framework provides an effective computational tool for predicting an‎d controlling solidification microstructures in laser powder bed fusion.

احمد كرمانپور , احمد رضائيان

امين جعفري رامياني

مهدي جوان بخت , بهزاد نيرومند