Optimization of Test Conditions for Evaluating Hydrogen Embrittlement Susceptibility of High-Strength Steel for Prestressed Concrete Poles

Abstract

We optimized the test conditions for evaluating the hydrogen embrittlement susceptibility of High-strength steel used in prestressed concrete. Through experiments, we clarified the effects of an applied potential and ammonium thiocyanate (NH4SCN) concentration on hydrogen content. An applied potential of −1.0 V versus Ag-AgCl Electrode (SSE) and an NH4SCN concentration of 1.0 wt. % were optimal for the test. We also determined the dimensions of the test cell and test temperature. Experiments in which we soaked different lengths of specimens and changed the solution volume to specimen area ratio led us to design a test cell with a soaking length of 15 cm and an inner diameter of 8 cm. A test temperature of 50°C was chosen for acceleration of hydrogen embrittlement.

Effect of Ammonium Thiocyanate on Hydrogen Absorption by Cathodic Charging in Weak Alkaline Solution

“…This method has been used to analyze the hydrogen absorption enhancement effect of promoters (As 2 O 3 and Na 2 S) in alkaline solutions. 25,26) In this study, we focus on cathodic charging in a weak alkaline solution, which is often used for hydrogen embrittlement tests, 27) and aim to clarify the mechanism underlying hydrogen absorption enhancement by NH 4 SCN in this condition. It is not obvious whether the Heyrovsky reaction is negligible under this condition, so we developed and used an analysis method based on fitting, with reference to the method of Qian et al 25,26) We constructed a kinetic model of the HER and HAR and investigated the hydrogen absorption enhancement effect of NH 4 SCN by analyzing the two reactions through fitting to i C and i ∞ measured in hydrogen permeation tests.…”