Effect of hydrogen on dislocation nucleation in alloy 718

A Modified Electrochemical Nanoindentation Setup for Probing Hydrogen-Material Interaction Demonstrated on a Nickel-Based Alloy

“…Later investigations also focused on the hardness evolution during the ECNI. [19][20][21][22][23] The measured hardness increase supports their hypotheses of a decreasing dislocation mobility due to hydrogen. Further explanations are an increase in lattice friction 20,21 as well as a classical solid solution strengthening contribution by hydrogen.…”

“…Struers OP-S solution was used as a last mechanicchemical polishing step. To remove the remaining deformation layer, electropolishing with a methanolic H 2 SO 4 solution was carried out in the Struers Lectropol applying 22 V for 40 s. 19 The microstructure was analysed using a laser confocal microscope LEXT OLS4100 (Olympus, Tokyo, Japan) for topography images, which were postprocessed with Gwyddion software. Scanning electron microscope (SEM) images and electron backscatter diffraction (EBSD) were carried out on a FEI 3D DualBeam workstation (Thermo Fisher Scientific, Waltham, MA, USA) with an EDAX Hikari XP EBSD camera (EDAX Inc., Mahwah, NJ, USA).…”

“…All electrochemical measurements were conducted with a Gamry 1010B potentiostat in a glycerine-based electrolyte with phosphoric acid in a mixing ratio of 2:1. 19 To promote the absorption of hydrogen, 1 g/L CH 4 N 2 S (Thiourea) was added as recombination poison. All reported potentials were measured against an Ag/AgCl reference electrode from ALS Japan with a platinum wire as counter electrode.…”

“…16,22,23 Overall, a variety of ECNI experiments have been performed, first on fundamental materials such as iron or technically clean nickel, 15,24 while more recent investigations have tried to meet the demands of industry by testing technically relevant engineering alloys. 19,20,25 For reliable ECNI experiments the hydrogen diffusion behaviour has to be taken into account. After charging the sample ex situ with hydrogen in an electrolyte by applying a cathodic potential to the specimen, the problem of prompt outgassing during sample transfer from the charging environment to the nanoindenter has to be considered.…”

Insight into hydrogen effect on a duplex medium-Mn steel revealed by in-situ nanoindentation test

“…Before testing, the sample was prepared to electropolishing level in a methanolic H 2 SO 4 solution. The ECNI test was done with Hysitron TI950 TriboIndenter integrated with a three-electrode electrochemical setup [26,29]. A Berkovich tip with a half angle of 65.3 was used inside the electrolyte designed for hydrogen charging, which is a glycerol-based borax solution containing 0.002 mol/L Na 2 S 2 O 3 to promote hydrogen absorption.…”