NASA Flags Casting Flaws in Alloy Used on ISS

A new technical bulletin warns that skipping homogenization in aluminum 2219 production leads to corrosion risks in human-rated spacecraft.

By The space-quantum Desk

[1]

Aluminum 2219 is an age-hardenable aluminum-copper alloy developed by Alcoa in 1954, rated for service up to 600 °F with excellent cryogenic properties, weldability, workability, and mechanical properties at low and high temperatures. [1] The problem lies in the casting stage: as-cast ingots can harbor disparate grain sizes, macrosegregation, and banded copper-rich intermetallics. [1]

[1] Multidirectional forging at 510 °C followed by warm rolling at 240 °C then reduces coarse Al2Cu particle area fraction from 5.5% to 1.0% and grain size from 230 micrometers to 58.6 micrometers. [1]

The bulletin reads less like a cautionary note and more like a structural argument for building quality into specifications before metal ever meets a mandrel — a discipline the industry has long understood but rarely codified at the procurement level.

NASA now recommends that homogenization be explicitly written into procurement specifications, with verification via before-and-after micrographs or DSC or XRD measurements. [1] For hardware rated to carry humans, the margin for a skipped step is zero.

no subsequent thermos-mechanical processing will remedy the deficiencies in properties, especially for larger ingot sizesNASA Technical Bulletin TB 26-07