Hydrogen diffusivity measurement and microstructural characterization of Custom 465 stainless steel

• Published in: Electrochimica acta Vol. 178; pp. 494 - 503
• Main Authors: Ifergane, S., Sabatani, E., Carmeli, B., Barkay, Z., Ezersky, V., Beeri, O., Eliaz, N.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-10-2015
• Subjects: Custom 465; Effects of strain; Hydrogen diffusion; Hydrogen permeation; Precipitation hardening stainless steel; Hydrogen permeation; Hydrogen diffusion; Effects of strain; Precipitation hardening stainless steel; Custom 465
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2015.08.016

Hydrogen diffusivity in Custom 465® martensitic precipitation hardened stainless steel is determined using electrochemical permeation tests. Hydrogen diffusivity in the solution annealed (SA) condition is approximately 10 times higher than in the aged H900 (480°C, 4h) condition because of hydrogen traps such as Ni3Ti nano-precipitates and reverted austenite. The microstructure of the alloy is characterized by TEM, XRD and ESEM/EBSD, both in the aged H900 and in the SA conditions. In the aged condition, η-Ni3Ti nano-precipitates with hexagonal structure and a rod-like shape are observed. In addition, reverted austenite is found at grain boundaries and inter-lath interfaces. In the SA condition, these microstructural features are not evident, which may explain the higher diffusivity measured. The diffusivity is almost unaffected by prior microplastic deformation of H900.