Quasi-static and dynamic fracture toughness of 316L stainless steel welds at cryogenic temperatures

Published

November 13, 2025

Author(s)

Jake Benzing, Enrico Lucon, Nicholas Derimow, Ross Rentz, Timothy Weeks

Abstract

This study investigates the cryogenic fracture toughness of four commercially welded 316L stainless steel plates using Charpy-sized single-edge bend [SE(B)] specimens and standard Charpy impact tests, under quasi-static and dynamic loading at 77 K (liquid nitrogen) and 4 K (liquid helium). Despite identical base metal specifications, the welds exhibited substantial variations in mechanical performance due to differences in welding processes and microstructure. The resultant analysis on temperature effects revealed that the only weld fabricated exclusively using gas tungsten arc welding (GTAW) consistently demonstrated the highest fracture toughness by a factor of two at 77 K and a factor of seven at 4 K. In contrast, a welding process that employed flux core arc welding (FCAW) for fill passes that also contained porosity resulted in the lowest overall toughness and greatest degradation (114 kJ/m2 at 77 K and 21 kJ/m2 at 4 K). In an effort to deconvolute the numerous competing mechanisms that contribute to toughness degradation, fractographic analysis revealed that minimal cleavage corresponded with the lowest δ-ferrite content, while the greatest amount of cleavage was linked to wormhole porosity and indicative of embrittlement. When analyzing loading rate effects, Charpy absorbed energy at 77 K broadly correlated with quasi-static toughness at 77 K for only three of the four welds. Dynamic toughness testing at 77 K with the SE(B) geometry and the multi-specimen method correlated poorly with quasi-static results using the SE(B) geometry and the single specimen method to produce J-R curves, but moderately (R2 ≈ 0.76) with Charpy absorbed energy, indicating a stronger dependence on strain rate than intrinsic material toughness. In summary, these findings highlight the critical role of welding process selection, microstructure control, and test methodology in qualifying welds for extreme cryogenic environments and caution against relying solely on Charpy impact testing when atypical weld structures are present.

Citation

Engineering Fracture Mechanics

Volume

330

Issue

111648

Pub Type

Journals

Download Paper

https://doi.org/10.1016/j.engfracmech.2025.111648

Local Download

Keywords

316L stainless steel, welding, liquid helium, liquid nitrogen, quasi-static fracture toughness, dynamic fracture toughness.

Citation

Benzing, J. , Lucon, E. , Derimow, N. , Rentz, R. and Weeks, T. (2025), Quasi-static and dynamic fracture toughness of 316L stainless steel welds at cryogenic temperatures, Engineering Fracture Mechanics, [online], https://doi.org/10.1016/j.engfracmech.2025.111648, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=960219 (Accessed November 26, 2025)