Methodology and experimental validation of analytical melt pool models for laser powder bed fusion

Abstract

Laser Powder Bed Fusion (LPBF) is a frequently used Additive Manufacturing (AM) technique for producing metal parts with complex shapes. One of the crucial factors in obtaining an optimal part is understanding the behaviour of the melt pool, a pool of liquid metal molten by a laser. Its size and shape are the result of a wide range of (processing) parameters, making it labour intensive and costly to identify an optimal processing range. To accelerate the identification of suitable processing conditions, this work presents a novel methodology that combines (semi-) analytical expressions of the melt pool width w and the aspect ratio R=d/w to compute the depth d over a large processing range. This range includes both conduction (R<1) and keyhole (R>1) mode melting regimes. The novelty of the presented approach is the prediction of absolute melt pool dimensions for both the conduction and keyhole regime. Furthermore, this methodology is extensively validated for three common LPBF materials: Titanium Ti-6Al-4V, Stainless Steel 316L and Inconel 718. The average errors obtained between model and experimental data of the melt pool width & depth in a relevant processing range (0,8<R<3) are 10,92% & 11,37%, 12,58% & 10,99% and 15,27% & 12,81% for the three materials respectively. With these results, this work shows that the proposed methodology performs well in predicting melt pool dimensions for a large processing range, both in terms of speed and accuracy.