Abstract

Titanium alloys are susceptible to hydrogen embrittlement (HE) failure when exposed to hydrogen-containing environments, and their microstructural characteristics significantly govern the HE susceptibility. In particular, the width of α lamella in α/β dual-phase titanium alloys is a critical microstructural parameter; however, its influence on hydrogen-induced damage behavior and the associated mechanisms remain to be systematically explored. In this study, the HE behavior of Ti-6Al-4V samples with coarse and fine α lamellar structures were systematically compared via electrochemical hydrogen charging, tensile testing, fracture observation, microhardness measurement, and microstructural characterization. The results show that the coarse lamellar structure exhibits high HE susceptibility, with extensive hydride precipitation. In contrast, benefiting from the dense α/β phase interfaces that modulate hydrogen partitioning and local stress states, the fine lamellar structure significantly suppresses hydride formation, demonstrating excellent HE resistance. This study provides experimental evidence for the microstructural optimization of titanium alloys for service in hydrogen-prone environments.

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