A 3D analytical modeling method for keyhole porosity prediction in laser powder bed fusion

In this work, a three-dimensional (3D) analytical modeling method is proposed for the prediction of keyhole porosity in laser powder bed fusion (LPBF) metal additive manufacturing. The proposed method consists of a physics-based analytical thermal model for keyhole melting mode and a pore formation model. The thermal model is used to calculate the molten pool size and vapor depression depth, with given process conditions and material properties. It consists of a moving point heat source on the part surface and a moving finite line heat source penetrating into the part. The pore formation model considers the process of bubble generation and trapping. It is used to calculate the volume fraction of pores in solidified molten pool, with the molten pool dimensions, vapor depression depth, velocity of fluid flow, frequency of bubble emission, and average bubble size as inputs. To verify the proposed method, the predictions of keyhole porosity are compared with documented experimental data of Ti6Al4V and display acceptable agreement. No finite element analyses are included in the proposed method, which can save computational resources. Thus, the proposed method is useful for the rapid prediction of keyhole porosity and can help understand the physics and optimize the process conditions in LPBF. The sensitivity of keyhole porosity to process conditions is also discussed.

Automated summary

This study proposes a three-dimensional analytical modeling method for predicting keyhole porosity in laser powder bed fusion metal additive manufacturing. The method includes a physics-based thermal model for keyhole melting mode and a pore formation model. The predictions of keyhole porosity are compared with experimental data and show good agreement.