Numerical study of temperature and cooling rate in selective laser melting with functionally graded support structures

Support structures are critical to the successful printing of the overhang structures in selective laser melting. The heat transfer performance of support structures has significant influence on the temperature distribution and cooling rate within the overhang structures which in turn determine the microstructure and residual stress. In the present study, functionally graded support structures have been proposed and their thermal performance has been numerically investigated, with the consideration of different materials, cooling times and gradedness values. It has been found that functionally graded support structures can maintain a higher temperature level than the conventional uniform support structure at the bottom of overhang, which is equivalent to an extra preheating effect. The temperature fluctuation and cooling rate at the bottom of overhang can also be reduced by adopting the functionally graded support structures.