Abstract
In this study, a physics-based analytical thermal modeling method is proposed for the estimation of temperature distribution, molten pool geometries, and vapor depression size in keyhole melting mode of laser powder bed fusion (LPBF) metal additive manufacturing, considering the influence of laser spot size. A closed-form thermal model is developed to consider the complex mechanisms of laser powder absorption in keyhole melting mode, which consists of two heat sources. A moving circular heat source solution is employed to calculate the temperature increase caused by the laser powder absorbed in the keyhole mouth due to the thermal effects of plasma. A moving cylindrical heat source solution with finite length is employed to calculate the temperature rise due to the laser powder absorbed by the keyhole walls. The radius of the circular and cylindrical heat sources is equal to the laser spot radius. The total temperature distribution in the keyhole mode is the superposition of the results of two heat source solutions. The geometries of molten pool and vapor depression are then determined by comparing the calculated temperature profile with the melting point and boiling point of the material, respectively. The proposed analytical thermal model has been experimentally validated. The predictions of molten pool size and vapor depression depth show good agreement with experimental results of Ti6Al4V in LPBF. The analytical modeling method has high computational efficiency because no finite element-based numerical calculations are incorporated in this method. Thus, the proposed analytical model will become a low-cost tool to help the researchers conduct rapid simulation of the melting process in LPBF and avoid the expensive trial-and-errors in experimental investigations.
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Wang, W., Liang, S.Y. Physics-based analytical modeling of keyhole mode in laser powder bed fusion. Int J Adv Manuf Technol 123, 2809–2818 (2022). https://doi.org/10.1007/s00170-022-10263-7
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DOI: https://doi.org/10.1007/s00170-022-10263-7