Fatigue of 316L stainless steel notched μμm-size components

• Analysis of fatigue experiments on 316L steel smooth and notched μm-size specimens.
• Application of elasto-plastic mechanical analyses to notched μm-size specimens.
• Fatigue criteria for infinite and finite lifetime, calibrated on experimental data.
• Gradient effect treated with hot-spot/volumetric approaches for lifetime estimation.
• The criteria can be applied for the numerical lifetime prediction of 316L stents.

The aim of the present paper is to provide an in-depth analysis of the fatigue-life assessment for μμm-size 316L stainless steel components. Such components find typical applications in the biomedical field, e.g., in cardiovascular stents. To this purpose, the present work analyzes experimental data on 316L stainless steel from literature for smooth and notched μμm-size components using a global computational approach. Several aspects are discussed: (i) the choice of an appropriate constitutive law for cyclic material behavior, (ii) fatigue criteria based on shakedown concepts for finite and infinite lifetime, in particular distinguishing between low, high and very high-cycle fatigue regimes (denoted as LCF, HCF and VHCF, respectively), and (iii) gradient effects in relation with hot-spot as well as average or mean volume approaches for the lifetime estimation. The results give a new insight into the lifetime design of μμm-size components and could be directly applied for the fatigue-life assessment of small size structures as, for instance, cardiovascular 316L stainless steel stents.