In selective laser melting, the rapid change of the temperature field caused by the rapid movement of the laser causes the instability of the melt pool flow, resulting in a generation of defects, such as lack of fusion, keyholing and balling effect, which greatly affect the performance of parts. In order to fully understand the temperature distribution and defect generation process of selective laser melting (SLM), experimental research, numerical simulation and analytical methods are mainly applied. The analytical method is suitable for the determination of the optimal process parameters because it is simple and consumes fewer resources. In a simulation, the absorptivity of the material is usually regarded as a constant, but experimental studies have shown that absorptivity is related to temperature, laser power, scanning speed, layer thickness and other process parameters. Considering the dynamics of thermal physical properties of Inconel 718, an improved analytical method was proposed and successfully applied to thermal analysis and the prediction of melt pool size. By comparing with the results of finite element simulation, experiment and other analytical solutions, the ease of use and effectiveness of the method are verified. Based on the prediction of the melt pool and the criterion of internal defects, the combination of process parameters that produce internal defects is calculated, which will make it possible to quickly obtain ideal process parameters.
The Analytical Prediction of Thermal Distribution and Defect Generation of Inconel 718 by Selective Laser Melting