AerMet 310 is the higher-strength step up from AerMet 100 within Carpenter Technology's AerMet family of secondary-hardening alloy steels. Like AerMet 100, it is not a stainless steel — its alloying is built around cobalt and nickel (nominally 15% Co, 11% Ni) with chromium and molybdenum additions (2.40% Cr, 1.40% Mo) and roughly 0.25% carbon, hardened through a martensitic quench followed by an aging treatment that precipitates fine alloy carbides rather than the copper- or titanium-based intermetallics used in PH stainless or maraging steels. That secondary-hardening mechanism is what lets AerMet alloys reach such a high strength-to-toughness combination without the brittleness typical of conventional through-hardened alloy steel at similar strength levels.

At a nominal 310 ksi (2137 MPa) ultimate tensile strength, AerMet 310 delivers toughness equivalent to alloys roughly 20 ksi lower in strength — a meaningful jump over AerMet 100 while retaining excellent ductility, fatigue resistance, and stress-corrosion cracking resistance. It is used in the same high-stress aerospace and defense structural roles as AerMet 100 — landing gear, actuators, structural tubing, drive shafts, and ballistic-tolerant components — where the extra strength margin is needed and the part geometry can tolerate AerMet 310's more demanding heat-treat and machining requirements.

AerMet 310 is a proprietary Carpenter Technology alloy (U.S. Patent 5,866,066) rather than an AISI/SAE, DIN, or UNS standard grade. No independently verifiable Wnr., DIN, or UNS cross-reference was found for this designation — specify and order this material by the AerMet 310 trade name and Carpenter's mill certification.

Nominal type-analysis figures per Carpenter Technology's published AerMet 310 data sheet. These match this page's prior content, which was correct as published — no correction needed here.

AerMet 310 is supplied and machined in the annealed condition — a 1775°F normalize followed by a 16-hour 1250°F overage anneal, which gives a maximum annealed hardness of 40 HRC. Carpenter's own machinability guidance places AerMet 310 as somewhat more difficult to machine than 4340 at Rockwell C 38, which puts it firmly in tough-alloy-steel territory rather than typical structural-steel territory: expect higher cutting forces, faster tool wear, and a stronger need for rigid setups than a plain 4340 part at the same hardness, driven by the cobalt content and the fine alloy-carbide dispersion left from the overage anneal.

As with AerMet 100, the practical machining strategy is to remove the bulk of stock in the annealed condition and hold final dimensions for after aging (900°F for 3-8 hours) wherever the application allows. AerMet 310 is not water quenched — oil or controlled air cooling is used to reach 150°F within the required window — and a stress relief at 350-400°F prior to any straightening operation is recommended if the part needs mechanical correction after heat treatment.

Turning figures follow Carpenter's published guidance of 280-350 SFM with carbide tooling in the annealed condition (~38-40 HRC). Other operations are scaled proportionally; verify with a test cut. Reduce speeds substantially once the part is aged.

Turning

Parting / Grooving

Milling