Study of the effect of heat treatment on fatigue crack growth behaviour of 316L stainless steel produced by selective laser melting

This study is focused on stainless steel type 316L produced by selective laser melting (SLM). This steel is very resistant to corrosion in acidic environments and has extremely good strength properties at elevated temperatures. It is also characterized by a very good weldability. These properties allow for various applications of 316L in different fields. The widespread application of 316L opens up various possibilities for production of parts using SLM. Therefore, it is important to characterize the fatigue crack growth behaviour. In the present paper, the crack growth behaviour of SLM 316L stainless steel has been investigated in its as-built condition and in different heat treatment conditions. The effect of build orientation on the crack growth path is also studied by performing fatigue crack growth tests on compact tension specimens built at 0 degrees and 45 degrees orientations relative to the build direction. A heat treatment above the recrystallization temperature followed by quenching is shown to create compressive residual stresses that improve the resistance against crack propagation considerably. The 45 degrees build orientation shows crack propagation at an angle to the initial notch plane, which reveals that anisotropy still persists after heat treatment.