Uphill Quenching of Aluminum Alloys

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Materials Performance and Characterization

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Uphill quenching is often not well understood and there are relatively few publications on the topic. Uphill quenching was originally developed by Alcoa approximately 50 years ago for aluminum alloys. It has also been referred to as “deep freezing” or “tri-cycle stress relieving.” Uphill quenching has been reported to provide residual stress reduction that may exceed 80 %. Therefore, uphill quenching is typically used to achieve dimensional stability in several critical types of aluminum parts. Uphill quenching is typically applied after quenching and before aging. The uphill quenching process consists of the immersion of the part into a cryogenic environment and after cooling is immediately followed by transferring to a hot-steam fixture to obtain a temperature gradient that maintains the mechanical properties gained with the heat treatment. When performed properly, uphill quenching results in low residual stresses and improved dimensional stability. This paper provides an overview of the uphill quenching process and its application in the heat treatment of critical aluminum alloy components such as large aerospace components.



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