Abstract
In this paper, a Paris law-based model is presented whereby crack propagation occurs under cyclic loading in air (fatigue) and in an aggressive environment (corrosion-fatigue) for the case of corner cracks (with a wide range of aspect ratios in the matter of the initial cracks) in finite-thickness plates of 316L austenitic stainless steel subjected to tension, bending, or combined (tension + bending) loading. Results show that the cracks tend during their growth towards a preferential propagation path, exhibiting aspect ratios slightly lower than unity only for the case of very shallow cracks, and diminishing as the crack grows (increasing the relative crack depth)—more intensely in the case of bending than in the case of tension (the mixed loading tension/bending representing an intermediate case). In addition, the crack aspect ratios during fatigue propagation evolution are lower in fatigue (in air) than in corrosion-fatigue (in aggressive environment).
Highlights
The 316L stainless steel is a structural material widely used in engineering, in particular in the nuclear industry, usually immersed in a very aggressive environment and subjected to fatigue
The change in the fatigue behavior of 316L stainless steel weldments is frequently related to microstructural modifications [2]
It can be observed that the crack propagation curves a/b-a/t associated with different initial geometries tend towards a preferential propagation path, which is different depending on the case of analysis
Summary
The 316L stainless steel is a structural material widely used in engineering, in particular in the nuclear industry (vessels for fission and fusion reactors), usually immersed in a very aggressive environment and subjected to fatigue (cyclic loading). In this framework, understanding its fatigue and corrosion-fatigue behavior is of the highest importance. Molybdenum content for austenitic stainless steel, tempering temperature for 13% chromium stainless steel, and volume percent ferrite for duplex stainless steel are metallurgical factors that contribute to corrosion-fatigue strength improvement These factors are strongly involved in corrosion pit formation and in corrosion-fatigue crack initiation processes [1]. The rotary swaged material improved corrosion resistance, while shot peening led to lower corrosion resistance [3]; increasing the shot peening time produces an improvement in the resistance to pitting corrosion [4]
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