Influence of microstructural defects and the surface topography on the fatigue behavior of additively-subtractively manufactured specimens made of AISI 316LEinfluss mikrostruktureller Defekte und der Oberflachentopographie auf das Ermudungsverhalten additiv-subtraktiv gefertigter Proben aus AISI 316L

As additive manufacturing offers only low surface quality, a subsequent machining of functional and highly loaded areas is required. Thus, a sound knowledge of the interrelation between the additive and subtractive manufacturing process as well as the resulting mechanical properties is indispensable. In this work, specimens were manufactured by using laser-based powder bed fusion (L-PBF) with substantially different sets of process parameters as well as subsequent grinding (G) or milling (M). Despite the substantially different surface topographies, the fatigue tests revealed only a slight influence of the subtractive manufacturing on the fatigue behavior, whereas the different laser-based powder bed fusion process parameters led to pronounced changes in fatigue strength. In contrast, a significant influence of subtractive finishing on the fatigue properties of the defect-free continuously cast (CC) reference specimens was observed. This can be explained by a dominating influence of process-induced defects in laser-based powder bed fusion material, which overruled the influence of surface machining. However, although both laser-based powder bed fusion parameter sets resulted in substantial defects, one set yielded similar fatigue strength compared to continuously cast specimens.

Automated summary

The study found that subtractive manufacturing had minimal impact on fatigue behavior, but different laser-based powder bed fusion process parameters significantly affected fatigue strength. Additionally, subtractive finishing had a significant influence on fatigue properties of defect-free continuously cast reference specimens.