Investigation of creep behavior of 316L stainless steel produced by selective laser melting with various processing parameters

Creep behavior of 316L stainless steel was experimentally investigated using small punch (SP) specimens produced by the selective laser melting (SLM) with various processing parameters. Five rectangular blocks were fabricated from gas atomized powder using the SLM. Various combinations of the processing parameters were used in the SLM process, such as the scanning speed and the laser power, when the energy density was kept as a constant. The scanning speed was increased from 336 to 784 mm/s, while the laser power was simultaneously increased from 165 to 385 W. The microstructural characteristics of each block were examined to verify the manufacturing conditions. Internal defects such as pores and un-melted powder were observed in the specimens fabricated when the low laser power was used. Small punch (SP) creep tests were carried out at 650 degrees C in the applied load range of 320-550 N. Creep-rupture life and Norton's power law creep deformation constants were measured. The results showed that even though the energy density condition was same for all of the creep specimens, those with higher laser power showed better creep resistance. Since it was known that a higher scanning speed could deteriorate the creep resistance, the higher creep resistance under the high scanning speed condition was indebted to the higher laser power used. The observed creep behavior of the SLM blocks was explained in relation to the microstructures.