AMS 5864 is an aerospace material specification for a premium quality corrosion resistant
precipitation hardenable steel alloy. Common names for the alloy are 13-8 or UNS S13800.
AMS 5864 material is in the form of plate.
This alloy is typically used where a combination of strength and corrosion resistance is required
in applications with service temperatures up to 600 deg F.
AMS 5864 requires vacuum induction melting and consumable electrode remelting.
Material to this standard is supplied in the solution heat treated condition that can be readily
heat treated to final properties during the manufacture of component parts.
To assure the results of the final precipitation hardening treatment; samples of the product are
precipitation hardened to same condition to insure consistency and that specs are met.

For more info on stainless steel grade 13-8 check out the longer video here.