Analytical Modeling of In-Process Temperature in Powder Bed Additive Manufacturing Considering Laser Power Absorption, Latent Heat, Scanning Strategy, and Powder Packing

Abstract

Temperature distribution gradient in metal powder bed additive manufacturing (MPBAM) directly controls the mechanical properties and dimensional accuracy of the build part. Experimental approach and numerical modeling approach for temperature in MPBAM are limited by the restricted accessibility and high computational cost, respectively. Analytical models were reported with high computational efficiency, but the developed models employed a moving coordinate and semi-infinite medium assumption, which neglected the part dimensions, and thus reduced their usefulness in real applications. This paper investigates the in-process temperature in MPBAM through analytical modeling using a stationary coordinate with an origin at the part boundary (absolute coordinate). Analytical solutions are developed for temperature prediction of single-track scan and multi-track scans considering scanning strategy. Inconel 625 is chosen to test the proposed model. Laser power absorption is inversely identified with the prediction of molten pool dimensions. Latent heat is considered using the heat integration method. The molten pool evolution is investigated with respect to scanning time. The stabilized temperatures in the single-track scan and bidirectional scans are predicted under various process conditions. Close agreements are observed upon validation to the experimental values in the literature. Furthermore, a positive relationship between molten pool dimensions and powder packing porosity was observed through sensitivity analysis. With benefits of the absolute coordinate, and high computational efficiency, the presented model can predict the temperature for a dimensional part during MPBAM, which can be used to further investigate residual stress and distortion in real applications.

Additive manufacturing of CuCr1Zr by development of a gas atomization and laser powder bed fusion routine

“…During LPBF, multilayer micro-welding processes are activated for generation of macroscopic structures, i.e., metal powder is transformed into bulk material of a grain size between 10 and 60 μm by remelting 20 to 100 μm layers on a substrate plate. Furthermore, a large temperature gradient is occurring, originating from the repetitive rapid heat and solidification during the distinct micro-welding processes of each layer [13,14]. This gradient influences significantly the microstructure of the LPBF-built parts and may result in defects like cracking [15] or part distortion [16].…”

“…Furthermore, an understanding of the melt pool induced by the micro-welding processes and the melt pool dynamics (see [17,18]) allows the adjustment of the LPBF-built microstructures [19]. For the consideration of the melt pool and temperature fields during the LPBF process, analytical and numerical approaches are available (see for example [14,20,21]).…”

Laser Powder Bed Fusion of Inconel 718: Residual Stress Analysis Before and After Heat Treatment

“…This model is based on a single track (no full layer). Ning et al [50] proposed an analytical model to predict the temperature using an absolute coordinate system at the part boundary. Unidirectional and bidirectional scan strategies are approached in this study.…”

“…Unidirectional and bidirectional scan strategies are approached in this study. With the predicted temperatures, part distortions and RS state can be further investigated [50].…”

“…Ideally, the models need to be accurate, high computationally efficient and intuitive; however, PBF-LB is a multi-physics complex problem to analyze [53]. The high computational cost is the main drawback to the development of more accurate models and methods of predicting and simulating the AM processes [50]. Validation of models that can accurately simulate and predict the RS of full complex parts built by AM have rarely been accomplished [45].…”