A novel strategy for estimating the diffusion behavior of hydrogen in metallic materials with the combined effect of stress corrosion and hydrogenation: Case study of 2.25Cr-1Mo-0.25V high-strength steel

Abstract

Hydrogen equipment for long-term service in complex hydrogen environment is threatened by the phenomenon of hydrogen-induced damage, and the combined effect of stress corrosion and hydrogen attack can intensify the formation and development of hydrogen damage. In this study, a new strategy to indirectly estimate the hydrogen diffusivity of metallic materials under tensile stress was proposed by combining the electrochemical hydrogen permeation test (EHPT), the hydrogen diffusion descriptive equation based on Fick's law, and hydrogen pre-charged tensile test. The results revealed that the hydrogen permeation curve obtained after considering the effect of the residual hydrogen extraction stage was highly approximate to the theoretical trend. The hydrogen embrittlement (HE) susceptibility of the pre-tensioned tensile and hydrogen-charged specimens increased with increasing stress. At tensile stress (0–400 MPa) the effective hydrogen diffusivity of 2.25Cr-1Mo-0.25 V steel was: Deff=1.1686+0.4842×exp(σ/277.869). The micrograph from the fracture surfaces also reflected the aggravated brittle fracture characteristics of the steel.