Abstract
A deep understanding of the laser-material interaction mechanism, characterized by laser absorption, is very important in simulating the laser metal powder bed fusion (PBF) process. This is because the laser absorption of material affects the temperature distribution, which influences the thermal stress development and the final quality of parts. In this paper, a three-dimensional finite element analysis model of heat transfer taking into account the effect of material state and phase changes on laser absorption is presented to gain insight into the absorption mechanism, and the evolution of instantaneous absorptance in the laser metal PBF process. The results showed that the instantaneous absorptance was significantly affected by the time of laser radiation, as well as process parameters, such as hatch space, scanning velocity, and laser power, which were consistent with the experiment-based findings. The applicability of this model to temperature simulation was demonstrated by a comparative study, wherein the peak temperature in fusion process was simulated in two scenarios, with and without considering the effect of material state and phase changes on laser absorption, and the simulated results in the two scenarios were then compared with experimental data respectively.
Highlights
The powder bed fusion (PBF) process is one of the earliest commercialized additive manufacturing (AM) processes, and is the most popular one, attracting more and more attention from industrial practitioners [1]
It is known that laser absorption of material affects the temperature distribution which influences the thermal stress development and the final quality of parts
In order to determine the suitability of the model in the temperature simulation of a laser metal PBF process, comparative studies with experimental work were conducted
Summary
The powder bed fusion (PBF) process is one of the earliest commercialized additive manufacturing (AM) processes, and is the most popular one, attracting more and more attention from industrial practitioners [1]. There are FE-based experiential studies which investigate the effects of process parameters and material properties in the PBF process on the quality of finished parts, such as laser power [7,9,10,11,12,13,14], scanning velocity [9,10,11,12,13,14,15], line energy [22,24], beam size [7,9,10,11], hatch space [7,10,12,24], layer thickness [15], track length [24], scanning patterns [6,23], volume shrinkage due to phase change from material in the powder state to the liquid state and to solid state [24,25], interval time between neighboring tracks [24], preheating temperature [9,10,15], and powder porosity [15].
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