This specification covers an aluminum alloy in the form of alclad sheet whose core grain size shall be ASTM No. 6 or finer.
This sheet has been used typically for severely formed structural parts which will be subsequently heat treated and painted or otherwise protected from corrosion, but usage is not limited to such applications.
Certain design and processing procedures may cause this sheet to become susceptible to stress-corrosion cracking after heat treatment; SAE ARP 823 recommends practices to minimize such conditions.
AMS4278B has been reaffirmed to comply with the SAE five-year review policy.