A NASA technical bulletin dated September 24, 2026, addresses manufacturing risks in aluminum alloy 2219, an age-hardenable aluminum-copper alloy developed by Alcoa in 1954 for service up to 600 °F. Its aerospace uses include space shuttle fuel tanks and International Space Station pressurized modules. The bulletin warns that improper casting and forging can produce microstructural defects that lead to a sub-optimal response to anodic surface treatments and greater corrosion susceptibility.

According to the document, as-cast ingots may contain disparate grain sizes, macrosegregation of alloying elements, and banded or clustered copper-rich intermetallics, which can yield low ductility, low strength and non-uniform properties. It states that unrecoverable discontinuities, particularly in larger ingots, cannot be remedied by later thermomechanical processing. Homogenization after conventional direct chill casting is described as imperative and should be written explicitly into procurement specifications, with verification through before-and-after micrographs, differential scanning calorimetry or X-ray diffraction. The bulletin also recommends multidirectional deformation, citing an example in which coarse Al2Cu particles fell from 5.5% to 1.0% and grain size from 230 micrometers to 58.6 micrometers.