Preprint Article Version 1 This version is not peer-reviewed

Effects of Scan Strategy on Thermal Properties and Temperature Field in Selective Laser Melting

Version 1 : Received: 31 July 2019 / Approved: 1 August 2019 / Online: 1 August 2019 (03:52:29 CEST)

How to cite: Mirkoohi, E.; Sievers, D.E.; Garmestani, H.; Liang, S.Y. Effects of Scan Strategy on Thermal Properties and Temperature Field in Selective Laser Melting. Preprints 2019, 2019080003 (doi: 10.20944/preprints201908.0003.v1). Mirkoohi, E.; Sievers, D.E.; Garmestani, H.; Liang, S.Y. Effects of Scan Strategy on Thermal Properties and Temperature Field in Selective Laser Melting. Preprints 2019, 2019080003 (doi: 10.20944/preprints201908.0003.v1).

Abstract

Temperature field is an essential attribute of metal additive manufacturing in view of its bearings on the prediction, control, and optimization of residual stress, part distortion, fatigue, balling effect, etc. This work provides an analytical physics-based approach to investigate the effect of scan strategy parameters including time delay between two irradiations and hatching space on thermal material properties and melt pool geometry. This approach is performed through the analysis of the distribution of material properties and temperature profile in three-dimensional space. The moving point heat source approach is used to predict the temperature field. To predict the temperature field during the additive manufacturing process some important phenomena are considered. 1) Due to the high magnitude of temperature in the presence of the laser, the temperature gradient is usually high which has a crucial influence on thermal material properties. Consequently, the thermal material properties of stainless steel grade 316L are considered to be temperature-dependent. 2) Due to the repeated heating and cooling, part usually undergoes several melting and solidification cycles. This physical phenomenon is considered by modifying the heat capacity using the latent heat of melting. 3) The multi-layer aspect of metal AM process is considered by incorporating the temperature history from the previous layer since the interaction of the successive layers has an impact on heat transfer mechanisms. 4) Effect of heat affected zone on thermal material properties is considered by the superposition of material properties in regions where the temperature fields of two consecutive irradiations have an overlap since the consecutive irradiations change the behavior of the material properties. The goals are to 1) investigate the effects of temperature-sensitive material properties and constant material properties on the temperature field. 2) Study the behavior of thermal material properties under different scan strategies. 3) Study the importance of considering the effect of heat affected zone on thermal material through the prediction of melt pool geometry. 4) Investigate the effect of hatching space on melt pool geometry. This work is purely employed physics-based analytical models to predict the behavior of material properties and temperature field under different process conditions, and no finite element modeling is used.

Subject Areas

selective laser melting; temperature modeling; melt pool geometry; hatching space; time delay

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