Effect of Surface Roughness on Fatigue Behavior of 316L Stainless Steel Produced by Binder Jetting Process

Tension-compression fatigue tests were performed on 316L stainless steel produced by binder jetting (BJ) process with the as-built and polished surface conditions to understand the effect of surface roughness on fatigue performance. The porosity was analyzed using X-ray CT scan to study the distribution and the correlation to fatigue crack initiation. The fatigue results indicate that BJ 316L shows a much lower fatigue strength compared to the ones produced by laser powder bed fusion (L-PBF) process and wrought 316L. Both ultimate tensile and yield strengths are much lower than L-PBF and wrought 316L. Porosity does not have a significant effect on fatigue crack initiation in the studied BJ 316L. The as-built surface roughness lowers the fatigue strength by roughly 21%. The BJ 316 yield strength is lower than the fatigue strength. Cyclic plastic shakedown was observed for samples tested near the fatigue strength. Cyclic ratcheting towards the negative strain was also observed. Pores in the sample show a distribution pattern related to the layer-by-layer deposition process.