Hydrogenation behavior of Cr-coated laser beam welds of E110 zirconium alloy

Hydrogenation Behavior of Cr-Coated Resistance Upset Welds of E110 Zirconium Alloy

“…The deposition of a chromium coating on the outer surface of RUW specimens can be used as a barrier layer for hydrogen permeation. The same result was found in several studies [25,32]. We found that Cr-coated RUW specimens have lower hydrogen absorption rates and higher activation energy compared to uncoated ones (Table 1).…”

“…The comparison of the hydrogenation behavior of RUW specimens and laser beam welds obtained in the previous study [25] showed that welding can cause a formation of transversely oriented hydrides in welded zones of specimens during hydrogenation procedures. In both types of welding, RUW and LBW, Cr coating deposition via magnetron sputtering can decrease such types of hydride precipitations in the case of low-temperature hydriding (360-450 • C).…”

“…Possible stress concentrations can be easily released in brittle hydride precipitates and at the α/δ phase boundaries [37]. The latter can lead to a negative effect on the mechanical properties of welded specimens [25]. Indeed, the noticeable increase in the hardness of RUW specimens after hydrogenation was determined (Table 2).…”

“…It can be observed that the absorption curve for the uncoated RUW specimen showed a significant decrease in the hydrogen absorption rate at a hydrogen concentration above 0.8 wt.% (Figure 2c). This indicates the decrease in absorption rate was caused by the formation of δ-zirconium hydrides, which have a lower hydrogen diffusion rate [25,29,30]. At the same time, the Cr-coated RUW specimen showed a smoother change in the hydrogen absorption rate.…”

“…Laser beam welding (LBW) can be applied to join spacer grids, while resistance upset welding (RUW) is commonly used to weld ends and fuel tubes to produce Zr fuel claddings. The authors previously investigated the hydrogenation behavior of Cr-coated laser beam welds made from an E110 zirconium alloy under normal operation and at an elevated temperature in hydrogen atmosphere [25]. The influence of other types of Zr alloy welding and next coating deposition should be analyzed to determine the need to apply a Cr coating to protect the ends and welds of nuclear fuel rods.…”