Hydrogen diffusivity measurement and microstructural characterization of Custom 465 stainless steel

• DOI: 10.1016/j.electacta.2015.08.016
• Publication Date: 2015-08-08T11:28:48Z
• Authors: S. Ifergane; E. Sabatani; B. Carmeli; Z. Barkay; V. Ezersky; O. Beeri; N. Eliaz
• Keywords: 0103 physical sciences; 14. Life underwater; 02 engineering and technology; 15. Life on land; 0210 nano-technology; 01 natural sciences

Abstract 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, 4 h) condition because of hydrogen traps such as Ni 3 Ti 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-Ni 3 Ti 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.