ABSTRACT This study explores the impact of surface condition on high‐cycle fatigue performance of a high‐nitrogen martensitic tool steel manufactured through powder metallurgy and hot isostatic pressing. In near‐net manufacturing applications, acid‐leaching pickling treatment and/or machining is used as a post‐treatment to remove the powder container. To assess the impact of these two treatments, surface properties and fatigue behavior were investigated in as‐pickled and machined surface conditions. The results revealed that as‐pickled samples had significantly higher surface roughness, higher surface compressive residual stress, higher surface hardness, lower amount of retained austenite, and lower carbon and nitrogen content than the machined ones. Despite high compressive residual stress in the as‐pickled samples, the surface roughness imposed a limit on fatigue strength. Additionally, the compressive residual stress altered the dominant fatigue crack initiation mechanism, shifting it from surface defects to internal non‐metallic inclusions in both surface conditions. These findings highlight the combined influence of surface roughness, residual stress, and inclusion characteristics in determining fatigue life.
Kalahroudi et al. (Fri,) studied this question.
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