Flow and fracture of austenitic stainless steels at cryogenic temperatures

In this paper, we have characterized the microstructural evolution and plastic flow fracture behaviours of AISI 304L 316LN stainless steel grades at liquid nitrogen temperature (77K) helium (4K). Uninterrupted tensile experiments, where sample is continuously deformed under quasi-static loading conditions until fracture, been carried out with a Single-Section Sample to obtain stress–strain characteristics two grades. Interrupted in which unloaded before performed novel Double-Section later characterize strain-induced martensitic transformation different levels deformation. The content martensite has determined post-mortem, using magnetic induction, electron backscatter diffraction quantitative light optical micrography. results obtained three methods show agreement, reveal that occurs faster greater extent than both 77K 4K. To authors’ knowledge, paper provide first experimental for samples tested temperature. addition, data volume fraction strain used identify temperature-dependent parameters kinetic model proposed by Olson Cohen (1975). Moreover, Mode I tests fatigue-precracked Compact Samples determine properties investigated materials “resistance curve procedure” (ASTM-E1820-20a). crack-growth resistance curves four here referred as ASTM Compliance Method, W–N Modified Method Normalization an original methodological contribution paper. While approaches yield similar toughness, only latter being fulfil all requirements standard ASTM-E1820-20a so calculated toughness can be accepted material property. comparison testing temperatures shows displays higher 304L. post-mortem analysis near surface revealed 316LN. Furthermore, more formed because deformation crack