Influence of High Temperature Oxidation on Hydrogen Absorption and Degradation of Zircaloy-2 and Zr 700 Alloys

Abstract

The present research was aimed at determining the effects of the oxide layers on hydrogen absorption, microstructure and mechanical properties of the Zircaloy-2 and Zr 702 alloys. The oxidation was made at 350 °C, 700 °C and 900 °C for 10 to 30 min in laboratory air, followed by hydrogen cathodic charging for 72 h and annealing at 400 °C for 4 h. The slow strain rate tests were carried out on oxidized, charged and annealed specimens. The oxidation resulted in thick and cracked, more for Zr 702 alloy, layer. After oxidation at 350 °C, the appearance of hydrides in Zircaloy-2 and absence of hydrides in Zr 702 alloy were observed. After oxidation at high temperatures no current flow was noticed at applied voltage up to 5 V, and no hydrogen or hydrogen cracks. The observed effects were attributed to the phase structure of investigated alloys at low hydrogen content.

Keywords

• zirconium alloys
• oxidation
• hydrogen degradation