Failure Behavior Analysis of 316L Crucible for Lead Bismuth Alloy Purification

After using 316L crucible for lead bismuth alloy purification for 6-7 months, the bottom of the crucible was perforated and the side wall was thinned obviously. X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectrometry (EDS), laser confocal microscope (LCM) and stereomicroscope were carried out to observe and analyze the surface morphology and cross-section components of 316L failure crucible, and the causes of perforation failure were analyzed combined with the service condition. The results showed that in the liquid lead bismuth alloy to been purified at 600 ℃, the 316L crucible had seriously dissolution corrosion and oxidation corrosion and the formation of uneven oxide layer could effectively prevent the matrix material. The areas not protected by oxide layer were enrichment of Sb element, and the matrix material was dissolved in the form of large pieces of material peeling off. The matrix had gradually grown corrosion holes. When corrosion holes grew to critical size or under the action of external force, the cracks at the edge nucleate and grew up and Sb element infiltrated into the matrix and dissolved the matrix along the crack propagation channel.