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Effect of laser scanning strategy on residual stress in selective laser melting
S. Tom, S. Chanda,
Published in American Institute of Physics Inc.
2023
Volume: 2584
   
Abstract
Selective laser melting (SLM) is a widely used additive manufacturing technique in which parts are made by melting a material layer by layer. SLM can be used to make complex parts with good mechanical properties. However, a large temperature gradient due to localized heating and cooling of the powder results in residual stress and deformation. Scan strategy is an important parameter that can reduce residual stress as it is directly related to the formation of temperature gradient during the process. Scan vector length, scan rotation angle, scan pattern, scan vector orientation and hatch distance are the major parameters involved in scanning. In this study, a 3D thermo-mechanical coupled numerical model is created to analyze the effect of scanning strategy on residual stress of SLM 316L steel parts. Thermal characteristics of the SLM process are modeled by considering a moving Gaussian heat source and advection-diffusion transport equations are solved along with phase change and mass conservation to obtain the temporal evolution and spatial distribution of temperatures in the manufactured component during the whole process. The obtained temperature history is fed into the mechanical model to estimate the distribution of residual stress over the entire domain. The mentioned methodology is used to perform preliminary numerical simulations for a process involving the fabrication of a component with eight layers by using a stripe scanning strategy and 30° scan rotation angle. The modeling results show that the residual stress in the Z (out of plane) direction is less than that in the other two directions. Also the residual heat which exists in the previous tracks and layers lead to the formation of larger melt pool in the subsequent layers, and the parts with the highest temperature have the minimum equivalent stress. Equivalent stress profile also shows that compressive stresses are formed at the edges and four corners of the part while tensile stress is formed at the center of the part. © 2023 Author(s).
About the journal
JournalAIP Conference Proceedings
PublisherAmerican Institute of Physics Inc.
ISSN0094243X