Custom 465 (UNS S46500, AMS 5936) is a precipitation-hardening martensitic stainless steel developed for aerospace structural components that need higher strength and fracture toughness than the widely used 17-4PH and 15-5PH grades can deliver. Its alloy base is roughly 12% chromium and 11% nickel with titanium and molybdenum additions; the titanium is what drives the precipitation-hardening reaction, forming fine intermetallic particles during aging that raise strength substantially above copper-hardened grades like 17-4PH.

That combination of very high strength (typically 1300-1700 N/mm² tensile depending on aging condition) and good fracture toughness makes Custom 465 a common choice for aircraft landing gear components, structural fittings, fasteners, and other highly loaded aerospace parts where 17-4PH or 15-5PH would not meet the strength or toughness requirement. Corrosion resistance is in the same general range as 304 stainless — good, but secondary to the strength and toughness properties that define this alloy's role. As with other PH martensitic grades, it is machined in the solution-annealed condition before aging, since hardness and cutting forces increase considerably once the alloy is aged to its final strength.

Custom 465 also contains small controlled additions of carbon, manganese, and silicon per AMS 5936; those minor-element limits were not independently verified for this listing and are omitted rather than guessed.

Custom 465 machines noticeably harder than the more common PH grades — its combination of high nickel and titanium-driven hardening gives it materially poorer machinability than 17-4PH or 15-5PH even in the solution-annealed condition. Cutting forces run higher, tool wear accelerates faster, and the material's toughness (the same property that makes it valuable structurally) means chips don't shear away as cleanly as they do on lower-toughness stainless grades. Low thermal conductivity, shared with all stainless steels, concentrates heat at the cutting edge and adds to the challenge.

Given the hardness and reduced machinability, a carbide grade with a very hard substrate and a thin PVD coating is generally the better choice over a CVD-coated grade better suited to easier-cutting stainless. Run at reduced cutting speeds compared with 17-4PH or 15-5PH, keep feeds firm and consistent to avoid dwelling and work hardening the surface, and do as much material removal as possible in the solution-annealed condition — cutting forces and wear increase substantially once the part is aged to its final 1300-1700 N/mm² strength range.

Values are for the solution-annealed condition, assuming favorable cutting conditions. Reduce further for aged/hardened material.

Turning

Parting / Grooving

Milling