Exploring factors controlling pre-corrosion fatigue of 316L austenitic stainless steel in hydrofluoric acid

摘要

While the low-cycle fatigue performance of metals is significantly influenced by corrosion, the corrosion damages and therefore the fatigue mechanisms induced by different solutions are different. In this paper, the pre-corrosion fatigue behavior of 316L austenitic stainless steel in hydrofluoric acid (HF) are studied. To characterize the corrosion type as well the extent of corrosion, the corrosion behavior of 316L austenitic stainless steel at different HF concentrations are investigated. Combined uniform corrosion and pitting corrosion are observed, with grooves formed by the superposition of several etched pits. Two methods are proposed to characterize corrosion damages, and the fatigue life is found to negatively correlate with the corrosion damage. To characterize fatigue crack initiation mechanisms, fracture surfaces of corroded fatigue specimens are examined with an emphasis on crack initiation sites. It is found that the crack initiates from multiple sources caused by multiple pits, and the surface average annular width of the pitting is found to be a more important factor controlling the fatigue life than the depth of pits. The results in this study are expected to provide insights into the understanding of failure mechanisms of equipment in fluorine chemical industry.