The heat transfer in and around a part being fabricated via Selective Laser Melting (SLM) is numerically simulated while considering the surrounding powder bed modeled to have an effective thermal conductivity. By accurately simulating the powder bed heat transfer during SLM, mechanical properties of parts can be better predicted. Heat transfer to previously-deposited layers and the build plate are also simulated. In order to validate the presented model, a thermocouple was embedded into a substrate used and a SLM system was utilized for performing two experiments. In the first set, various laser power and scan speed combinations were employed while passing the laser over the thermocouple-embedded substrate. This procedure calibrated the numerical model and demonstrated that the heat transfer due to convection and radiation during deposition of a single layer is approximately 10-15% of initial laser power input. The final experiment consisted of building a thin wall of SLM of 17-4 PH stainless steel (SS). The effects of scan pattern and part size on the temperature response of and around the part are demonstrated as significant. Distinct heating and cooling rates are also provided for these various cases; indicating the dependency of final microstructure on part size and the utilized scan pattern.
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