Hydrogen absorption cracking of zirconium alloy in the application of nuclear industry

► The grain size has a pronounced effect on hydrogen absorption cracking. ► Hydrogen absorption amount has a decisive effect on hydrogen absorption cracking. ► Hydrides in saturated/unsaturated hydrogen samples were analyzed by TEM/HRTEM. ► The decomposition temperatures of ɛ → δ and δ → α are about 600 °C and 700 °C respectively. ► The expansions of δ- and ɛ-hydrides during hydrogen absorption were evaluated.