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In this paper, the effect of shot peening and cryogenic turning on the surface morphologyof the metastable austenitic stainless steel AISI 347 was investigated. In the shot peeningprocess, the coverage and the Almen intensity, which is related to the kinetic energy of thebeads, were varied. During cryogenic turning, the feed rate and the cutting edge radiuswere varied. The manufactured workpieces were characterized by X-ray diffractionregarding the phase fractions, the residual stresses and the full width at half maximum.The microhardness in the hardened surface layer was measured to compare the hardeningeffect of the processes. Furthermore, the surface topography was also characterized. Thenovelty of the research is the direct comparison of the two methods with identical work-pieces (same batch) and identical analytics. It was found that shot peening generally leadsto a more pronounced surface layer hardening, while cryogenic turning allows the hard-ening to be realized in a shorter process chain and also leads to a better surface topog-raphy. For both hardening processes it was demonstrated how the surface morphology canbe modified by adjusting the process parameter.
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.