Hydrogen embrittlement of retrogression-reaged 7xxx-series aluminum alloys—a comprehensive review

Hydrogen embrittlement remains a crucial concern in industries that rely on high-strength materials. Exposure to hydrogen poses a significant threat to the mechanical integrity of such materials. This review article briefly discusses the fundamentals of hydrogen embrittlement, including its mechanisms and the effects of various factors, such as chemical composition and environmental conditions. Several heat treatments have been developed to eliminate the risk of hydrogen embrittlement. Among various suggested heat treatments, the retrogression-reaging (RRA) treatment has proven effective in optimizing the balance between mechanical properties and resistance to hydrogen embrittlement. This review highlights the role of RRA treatment in modifying the microstructure of Al-Zn-Mg alloys to enhance their ability to resist hydrogen embrittlement, building on existing literature. An interesting aspect explored in this article is the intricate relationship between pre-deformation and subsequent RRA treatment. Additionally, the review discusses the use of RRA as a post-weld heat treatment to mitigate the susceptibility of weldments to hydrogen embrittlement. A comprehensive exploration of these topics is beneficial for a thorough understanding of the multifaceted functions of RRA treatment. However, despite its advantages, the widespread adoption of RRA treatment in the industry is hindered by certain challenges. This review addresses these challenges, offering insights into the latest strategies to overcome them.