Hydrogen embrittlement on {alpha}-iron in high alkaline environment

Book · Sat Dec 31 04:00:00 EST 1994

OSTI ID:70154

Hu, R; Habashi, M; Galland, J ^[1]

---

1. Ecole Central Paris, Chatenay-Malabry (France)

The partial pressure of hydrogen in concrete`s pore is very low. This hydrogen is due to the chemical reaction between the silica fumes and the alkaline solutions filling the concrete`s pore. Silica fumes are added in the concrete to increase its compression resistance. If the hydrogen pressure is low, the risk of hydrogen embrittlement is also low. However, for constructional works destined to endure more than 50 years, is this risk negligible? To answer this question, the authors have studied the hydrogen embrittlement on {alpha}-iron in alkaline solutions, in the pH range 9.5 to 13.3, presenting the liquids found in the concrete`s pores after different aging, periods. Cathodic charging has been performed for low current densities in the range 0.25 to 90 A/m{sup 2} simulating several partial pressures of hydrogen on the {alpha}-iron surface with and without EDTA inhibitor. The deformation rate was 2.5{times}10{sup {minus}5} s{sup {minus}1}. Finally {alpha}-iron samples and tensile specimens have been immersed in a mixture of silica fumes and an alkaline solution at pH 13.3 in an autoclave during 1,000 hours with the aim to measure the outgassed quantity of hydrogen under vacuum at 600C and to measure also the hydrogen embrittlement. The main conclusions of this study are as following: (1) Hydrogen embrittlement is promoted by oxide Fe{sub 3}O{sub 4} film rupture and/or hydroxide Fe(OH){sub 2}. This mechanism is efficient for current densities equivalent to a cathodic potential lower or equal to {minus}1V/NHE. (2) Silica fumes in contact with a solution of pH 13.3 provoke hydrogen release and its diffusion into the {alpha}-iron, but this quantity is not enough to embrittle it.

• OSTI ID: 70154
• Report Number(s): CONF-940222--
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ASHES
CORROSION
CORROSION INHIBITORS
CORROSIVE EFFECTS
EXPERIMENTAL DATA
HYDROGEN EMBRITTLEMENT
IRON
IRON HYDROXIDES
IRON OXIDES
PH VALUE
POTASSIUM CARBONATES
POTASSIUM HYDROXIDES
REINFORCED CONCRETE
SODIUM CARBONATES
SODIUM HYDROXIDES
WASTE PRODUCT UTILIZATION