Interfacial hydrogen localization in austenite/martensite dual‐phase steel visualized through optimized silver decoration and scanning Kelvin probe force microscopy

Abstract

The hydrogen distribution in an austenite-martensite dual-phase steel was investigated using silver decoration and scanning Kelvin probe force microscopy. The silver decoration technique optimized for spacial resolution reveals interfacial segregation of hydrogen along the plate-type martensitemartensite grain boundaries. In addition, the scanning Kelvin probe force microscopy kinetically elucidates that hydrogen preferentially diffused out from the martensite-martensite grain boundaries. These preferential sites of hydrogen desorption correspond to the regions of hydrogen-assisted damage.

Current Challenges and Opportunities in Microstructure-Related Properties of Advanced High-Strength Steels

“…Another aspect that makes the proof of the prevalence of certain HE mechanisms so challenging are the tremendous experimental difficulties associated with imaging the concentration of hydrogen at a microstructural scale. [3,17,27,52,176,[295][296][297][298][299][300] Therefore, this section does not aim at developing a detailed review of all possible HE effects as covered already by several publications in this field, [50,205,279,284,[301][302][303][304][305] but instead emphasis is placed on the description of the current research status of HE in the field of AHSS. From this analysis the most critical problems and challenges for understanding HE mechanisms in AHSS are filtered, with the intention to shed light on future research directions.…”

In situ observations of silver-decoration evolution under hydrogen permeation: Effects of grain boundary misorientation on hydrogen flux in pure iron

“…Moreover, multi-scale hydrogen mapping is easily enabled through the use of light microscopy and scanning electron microscopy on the silver-decorated surface [8]. The observed results were demonstrated to have a significant correlation with damage initiation sites [9,12,15].…”

“…For hydrogen visualization, most of the recent technological efforts have been focused on three specific topics: quantification of the local hydrogen content [5][6][7], multi-scale hydrogen distribution observations [8,9], and kinetically resolved hydrogen mapping [10][11][12]. In recent studies [12][13][14], scanning Kelvin probe force microscopy (SKPFM) has been reported to enable sequential kinetic analysis of microstructural hydrogen diffusion/segregation.…”

“…In addition, the silver decoration technique has been noted as a complimentary method for SKPFM, as silver decoration enables hydrogen mapping over a short time range, e.g., within a few hours in ferritic steels. Hydrogen diffusion/segregation at weak trap sites can, therefore, be visualized by silver decoration [8].…”

“…Silver deposition on a pure iron specimen surface has been clarified to stem from hydrogen evolution, and its detailed behavior such as an effect of applied potential has been characterized through electrochemical analysis elsewhere [17,18]. In previous studies, the authors have demonstrated the silver decoration technique for fracture surfaces [19] and microstructural interfaces [8]. For a sake of clarify, in this study, the in situ silver decoration experiment was carried out under hydrogen permeation.…”