The Room Temperature Creep of Selective Laser Melted 316L Stainless Steel Investigated by Nanoindentation

The unique cellular sub-grain caused by selective laser melting (SLM) and its effect on nanoindentation creep were investigated in the SLM 316L stainless steel by nanoindentation and microstructure analysis. The load of the first pop-in of the SLM 316L sample was higher than that of the annealed sample, indicating that dislocation nucleation was inhibited. The cellular sub-grains and the high density of dislocations were observed in the SLM 316L sample, which greatly suppressed the primary creep and steady-state creep of the SLM 316L sample compared with the annealed sample. The creep stress exponent of all the samples varied from 35.7 to 62.5, indicating that the creep process was dominated by the mechanism of dislocation movement. The cellular sub-grain boundary and high density of dislocations inhibited the motion of dislocation, which were responsible for the improved creep resistance of the SLM 316L steel.