AerMet 100 is an ultra-high-strength, secondary-hardening martensitic alloy steel (UNS K92580, AMS 6532 / AMS 6478) containing nominally 13.4% cobalt, 11.1% nickel, 3.1% chromium, 1.2% molybdenum and 0.23% carbon, with iron as the balance. Vacuum induction melted and vacuum arc remelted, it develops a typical tensile strength of 1,965 MPa (285 ksi) with a plane-strain fracture toughness near 126 MPa√m (115 ksi√in), roughly double the toughness of other steels at the same strength level. It is not corrosion resistant, and service is limited to about 427 °C.
Jiangyin Jiangnan Metal Co., Ltd., an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, forges AerMet 100 into rings, seamless rolled rings, shafts, discs, blocks and bars to customer drawing, supplied with EN 10204 3.1 or 3.2 certification and ultrasonic testing to EN 10228-3, SEP 1921 or ASTM A388.
What AerMet 100 Actually Is
AerMet 100 was developed by Carpenter Technology to solve a problem that had constrained ultra-high-strength steel design for decades: strength and toughness normally trade against each other.
Push a conventional low-alloy steel such as 4340 past about 1,900 MPa and it becomes dangerously notch-sensitive, so a small flaw can run. AerMet 100 holds roughly 1,965 MPa while retaining a plane-strain fracture toughness near 126 MPa√m, so a component can be designed to a much larger critical flaw size without accepting brittle behaviour. In practice that means a longer inspection interval and a part that tolerates the damage real service inflicts on it.
The mechanism is secondary hardening. High cobalt and nickel suppress dislocation recovery during aging and promote a fine, uniform dispersion of M2C molybdenum carbides in a tough martensitic matrix. Because that dispersion is undermined by inclusions, the alloy must be double-vacuum melted (VIM followed by VAR) to keep oxygen, sulphur and non-metallic inclusion counts low enough to realise the toughness. Melt route is not negotiable on this grade the way it sometimes is on lower ones.
The most common misclassification. AerMet 100 is frequently listed online, including by suppliers, as a stainless steel or a nickel alloy. It is neither. At roughly 3.1% chromium it sits well below the ~10.5% threshold for stainless behaviour, and its nickel is an alloying addition to an iron matrix rather than a base. Treat it as an alloy steel, and specify a protective finish for any humid or marine exposure.
You will find this page filed under Nickel Alloy in our catalogue, which follows the long-standing convention among aerospace stockists of grouping high-nickel specialty grades together. The metallurgy, however, is that of an alloy steel, and the properties below should be read on that basis.
The practical consequence for a forging buyer: AerMet 100 is a strength-and-toughness alloy, not an environment-resistant one. It is the right choice for a highly loaded structural part where fracture control governs the design. It is the wrong choice for hot-section or chemically aggressive service, where a nickel-base superalloy or a true stainless grade belongs.
AerMet 100 at a Glance
- Forms we forge
- Rings, seamless rolled rings, shafts, stepped shafts, discs, blanks, sleeves, bushings, blocks, flanges and round bars, all to customer drawing.
- Delivery condition
- Normalized and overaged (annealed, ≤40 HRC) ready for your heat treatment, or fully solution treated and aged to the specified condition.
- Certification
- EN 10204 3.1 mill certificate as standard; EN 10204 3.2 third-party witnessed on request.
Chemical Composition
| Element | Nominal % | Typical range % | Metallurgical role |
|---|---|---|---|
| Cobalt (Co) | 13.40 | 13.00–14.00 | Suppresses dislocation recovery; enables secondary hardening |
| Nickel (Ni) | 11.10 | 11.00–12.00 | Raises matrix toughness, lowers transition temperature |
| Chromium (Cr) | 3.10 | 2.90–3.30 | Hardenability; too low for stainless behaviour |
| Molybdenum (Mo) | 1.20 | 1.10–1.30 | Forms the strengthening M2C carbides |
| Carbon (C) | 0.23 | 0.21–0.25 | Carbide former; controls peak hardness |
| Iron (Fe) | Balance | Balance | Matrix |
Phosphorus, sulphur, silicon, manganese, oxygen and nitrogen are held to low residual limits by the VIM-VAR route. Refer to AMS 6532 for the controlling maxima applicable to your order.
Mechanical Properties
| Orientation | 0.2% Yield | UTS | Elong. | R of A | CVN | KIC |
|---|---|---|---|---|---|---|
| Longitudinal | 1,724 MPa 250 ksi |
1,965 MPa 285 ksi |
14% | 65% | 41 J 30 ft-lb |
126 MPa√m 115 ksi√in |
| Transverse | 1,724 MPa 250 ksi |
1,965 MPa 285 ksi |
13% | 55% | 34 J 25 ft-lb |
110 MPa√m 100 ksi√in |
| AMS 6532 minimum | 1,620 MPa 235 ksi |
1,930 MPa 280 ksi |
n/a | n/a | n/a | ≥100 ksi√in |
Hardness response to aging temperature
| Condition | Hardness HRC | Comment |
|---|---|---|
| As hardened, not aged | 51.0–53.0 | Before secondary hardening |
| Aged 468 °C (875 °F) | 54.5–55.5 | Peak hardness Lowest allowed age temp. |
| Aged 482 °C (900 °F) | 53.0–54.0 | Best strength/toughness balance Standard cycle |
| Aged 496 °C (925 °F) | 51.0–52.5 | Overaged: higher toughness, lower strength |
| Overage annealed 677 °C 16 h | ≤40 max | Machining condition |
Physical Properties
| Property | Metric | Imperial |
|---|---|---|
| Density | 7.94 g/cm³ | 0.287 lb/in³ |
| Modulus of elasticity | 194 GPa | 28.2 × 10³ ksi |
| Mean CTE, 25–204 °C (heat treated) | 10.58 × 10⁻⁶ /°C | 5.88 × 10⁻⁶ /°F |
| Mean CTE, 25–427 °C (heat treated) | 11.25 × 10⁻⁶ /°C | 6.25 × 10⁻⁶ /°F |
| Critical temperature Ac1 | 574 °C | 1,065 °F |
| Critical temperature Ac3 | 829 °C | 1,525 °F |
| Max. service temperature | approx. 427 °C | approx. 800 °F |
| Magnetic response | Ferromagnetic in both annealed and aged conditions | |
AerMet 100 vs 300M vs 4340
These are the three grades that actually compete for the same fracture-critical, highly loaded parts. The strength numbers look close for two of them. The toughness numbers do not.
| Property | AerMet 100 | 300M | AISI 4340 |
|---|---|---|---|
| UNS / spec | K92580 / AMS 6532 | K44220 / AMS 6417 | G43400 / AMS 6414 |
| Typical UTS | 1,965 MPa Best | 1,930 MPa | 1,240–1,450 MPa |
| Typical yield | 1,724 MPa Best | 1,586 MPa | 1,080–1,300 MPa |
| Fracture toughness KIC | ~126 MPa√m Best | ~65 MPa√m | ~60 MPa√m |
| Hardness | 53–54 HRC | 54–56 HRC | 38–50 HRC |
| Melt route required | VIM + VAR | VAR or VIM-VAR | Air melt or VAR |
| Corrosion resistance | Coating needed | Coating needed | Coating needed |
| Relative material cost | Highest | Moderate | Lowest |
| Best suited to | Fracture-critical structure where a flaw must not run | High strength where toughness is secondary | General high-strength machinery |
The gap, drawn to scale
The second chart carries the selection case. At effectively identical tensile strength, AerMet 100 delivers roughly twice the fracture toughness of 300M. Where inspection interval or critical flaw size drives the design, that difference usually justifies the material premium. Where it does not, 300M or 4340 is the more economical specification, and we forge both.
Strengths and weaknesses of each grade
- Highest combined strength and toughness available in a steel
- Excellent SCC and fatigue crack growth resistance
- Weldable without preheat
- Minimal distortion in heat treatment
- Highest material cost of the three
- VIM-VAR melt mandatory, so longer lead time
- Tight forging and aging windows
- Requires a protective coating
- Near-AerMet strength at moderate cost
- Well established in landing gear service
- Broad supply base and stock availability
- Roughly half the fracture toughness
- Notch sensitive at full strength
- Hydrogen embrittlement risk on plating
- Lowest cost, widest availability
- Easy to machine and heat treat
- Well characterised across the industry
- Substantially lower strength ceiling
- Limited toughness at high hardness
- Section size limits on hardenability
Corrosion Behaviour: Read Before Specifying
This is the point most often reported incorrectly on supplier pages, so it is worth being direct about it.
| Property | Rating | Practical consequence |
|---|---|---|
| General / atmospheric corrosion | Restricted | Will rust in humid or marine exposure. Cadmium plate, aluminium-ceramic coating, IVD aluminium or paint is normally required |
| Stress corrosion cracking | Excellent | High KISCC in 3.5% NaCl compared with other steels at the same strength level |
| Fatigue & crack growth | Excellent | Supports high design stresses with good notch tolerance |
| Oxidation above 427 °C | Not suitable | Not a superalloy; specify a nickel-base grade for hot-section service |
| Hydrogen embrittlement | Susceptible | Bake after plating per the applicable process specification |
Resistance to stress corrosion cracking is not the same as corrosion resistance. AerMet 100 resists crack propagation under sustained load in a chloride environment far better than competing ultra-high-strength steels, but the bare surface still corrodes. Both statements are true at once, and confusing them is where most of the inaccurate material online comes from.
How We Forge AerMet 100
Forging parameters for AerMet 100 are tighter than for ordinary alloy steel, because finishing too hot coarsens prior-austenite grain size and permanently caps the fracture toughness the part can reach after heat treatment. Our practice follows the alloy producer's published guidance.
| Stage | Parameter | Why it matters |
|---|---|---|
| Primary breakdown | Max. start 1,232 °C (2,250 °F) | Above this, incipient melting and grain coarsening risk |
| Finish forging | From 982 °C (1,800 °F) | Sets the final worked structure |
| Finishing temperature | Below 899 °C (1,650 °F) | Required to optimise heat-treated properties |
| Post-forge cooling | Air cool to room temp. | Controlled transformation |
| Anneal | 677 °C × 16 h | Softens to ≤40 HRC for machining |
| Normalize | 899 °C × 1 h, air cool | Restores properties in the low-strain dead zone |
Forging capability
| Form | Typical size range | Notes |
|---|---|---|
| Forged / seamless rolled rings | OD 200–2,500 mm | Rectangular or contoured section |
| Shafts & stepped shafts | Ø 80–600 mm | Length to drawing |
| Discs & blanks | Ø 150–1,500 mm | Solid or trepanned |
| Sleeves & bushings | OD 150–1,200 mm | Bored and stress relieved |
| Blocks & rectangles | To drawing | Sawn or machined faces |
| Round bars | Ø 60–500 mm | Peeled or black |
Heat Treatment & Machining
| Step | Cycle | Critical control point |
|---|---|---|
| 1. Normalize | 899 °C × 1 h, air cool | Neutral atmosphere, salt bath or vacuum; AerMet 100 decarburises readily |
| 2. Overage anneal | 677 °C × 16 h, air cool | Optimum machining hardness, ≤40 HRC max. |
| 3. Solution treat | 885 °C ±14 °C × 1 h | Thermocouple must be attached to the load, not the furnace |
| 4. Quench | Cool to 66 °C in 1–2 h | Do not water quench. Oil quench sections over Ø50 mm / 25 mm thick; smaller sections air cool |
| 5. Cold treat | −73 °C × 1 h, air warm | Required to reach full toughness capability |
| 6. Age | 482 °C ±6 °C × 5 h, air cool | Never age below 468 °C (875 °F). |
If mechanical straightening is needed, a low-temperature stress relief at 177–204 °C for 5 hours after the refrigeration step gives the best combination of ductility and yield strength for straightening. Distortion during heat treatment is generally minimal.
Machining
Rough machine in the annealed or solution-treated condition and hold final critical dimensions for after aging wherever tolerance stack-up allows. AerMet 100 is somewhat harder to machine than 4340 at 38 HRC; carbide tooling at 85–107 m/min (280–350 SFM) is the recommended starting point. A stress relief at 427 °C for 1–3 hours after rough machining is worthwhile on thin or asymmetric parts.
Testing, Inspection & Certification
| Test | Standard | Scope |
|---|---|---|
| Chemical analysis | Spectrometric, per AMS 6532 | Heat / ladle analysis on every heat |
| Mechanical testing | ASTM A370 / ASTM E8 | Tensile and hardness; Charpy V-notch on request |
| Fracture toughness | ASTM E399 | KIC on request for fracture-critical parts |
| Ultrasonic testing | EN 10228-3, SEP 1921, ASTM A388, MIL-STD-2154 Cl. A | Acceptance class agreed at order stage |
| Magnetic particle | ASTM E1444 / ASTM A275 | Surface and near-surface indications |
| Grain size | ASTM E112 | On request; confirms forge finishing control |
| Dimensional | To customer drawing | Full report with the shipment |
| Material certificate | EN 10204 3.1 / 3.2 | 3.2 witnessed by SGS, BV, TÜV, Lloyd's or your own inspector |
On melt route and traceability. Genuine AerMet 100 must be VIM-VAR melted. If you are offered AerMet 100 forgings without a VIM-VAR mill certificate traceable to the melt heat, ask for the documentation before ordering, from us or from anyone else. Air-melt or ESR-only material with a similar analysis will not deliver the fracture toughness the alloy is specified for.
Where AerMet 100 Is Usually Specified
Aircraft landing gear
Cylinders, pistons, axles and trunnions where a fracture-critical part must tolerate a detectable flaw.
Jet engine shafts
Rotating shafts operating below 427 °C that need high specific strength.
Drive shafts & actuators
Highly loaded torque and linear actuation components in aerospace platforms.
Structural members
Fittings, links, lugs and structural tubing carrying concentrated loads.
High-strength fasteners
Bolts and studs where preload capacity is limited by the material, not the geometry.
Motorsport & downhole tooling
Competition driveline parts and high-load downhole components where toughness governs.
A simple selection framework
Frequently Asked Questions
Neither. AerMet 100 is an ultra-high-strength, secondary-hardening martensitic alloy steel with iron as the balance. It contains only about 3.1% chromium, far below the roughly 10.5% needed for stainless behaviour, and its 11.1% nickel is an alloying addition, not a matrix base. It is correctly classified as an alloy steel under UNS K92580 and specified by AMS 6532 and AMS 6478.
In the standard solution-treated, refrigerated and aged condition, AerMet 100 develops a typical ultimate tensile strength of about 1,965 MPa (285 ksi) with a 0.2% offset yield strength of about 1,724 MPa (250 ksi). AMS 6532 sets the specification minimum at 1,930 MPa (280 ksi) UTS and 1,620 MPa (235 ksi) yield. Typical hardness after the standard 482 °C age is 53–54 HRC.
No. AerMet 100 is not a corrosion-resistant alloy. With only about 3.1% chromium it will rust in humid or marine service and requires a protective finish such as cadmium plating, aluminium-ceramic coating or paint. What it does offer is exceptional resistance to stress corrosion cracking and fatigue crack growth at its strength level, which is a different property from general corrosion resistance.
AerMet 100 is generally considered for continuous service up to about 427 °C (800 °F). Above that, strength falls away and the aged microstructure begins to over-temper. It is not a high-temperature superalloy and should not be substituted for nickel-base grades such as Inconel or Incoloy in hot-section service.
AerMet 100 is produced by vacuum induction melting followed by vacuum arc remelting (VIM + VAR). This double-vacuum route is required to reach the low oxygen, sulphur and inclusion levels that give the alloy its fracture toughness. Air-melt or electroslag-only material does not meet AMS 6532 and should not be accepted as AerMet 100.
Normalize at 899 °C for 1 hour and air cool; overage anneal at 677 °C for 16 hours for machinability; solution treat at 885 °C ±14 °C for 1 hour; cool to 66 °C within 1 to 2 hours (oil quench for sections over 50 mm; water quenching is not recommended); refrigerate at −73 °C for 1 hour; then age at 482 °C ±6 °C for 5 hours and air cool. AerMet 100 must never be aged below 468 °C.
AerMet 100 reaches roughly 1,965 MPa UTS with about 126 MPa√m fracture toughness. 300M reaches a similar 1,930 MPa but with far lower toughness, around 60 to 70 MPa√m. 4340 typically runs 1,240 to 1,450 MPa with toughness near 60 MPa√m. The distinguishing feature of AerMet 100 is that it combines 300M-class strength with roughly double the fracture toughness, at a much higher material cost.
Jiangyin Jiangnan Metal Co., Ltd. produces AerMet 100 as open-die forged rings, seamless rolled rings, shafts, stepped shafts, discs, blanks, sleeves, bushings, blocks, flanges and round bars, forged to customer drawing. Forging starts at a maximum of 1,232 °C with finish forging from 982 °C and finishing below 899 °C, followed by air cooling, annealing and normalizing to restore properties in the low-strain dead zone.
EN 10204 3.1 mill certification is supplied as standard, with EN 10204 3.2 third-party witnessed certification available on request. Ultrasonic testing is performed to EN 10228-3, SEP 1921, ASTM A388 or MIL-STD-2154 Class A, with the acceptance class agreed at order stage.
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, that forges AerMet 100 rings, shafts, discs and bars to customer drawing. Reach the sales team on +86-189-2135-9659 or at sales@steelforgepieces.com. We ship worldwide from the Shanghai and Zhangjiagang port areas.
About Jiangyin Jiangnan Metal Co., Ltd.
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory based at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. We forge rings, seamless rolled rings, shafts, discs, sleeves, blocks, flanges and bars in carbon steel, alloy steel, tool steel, stainless steel, nickel alloys and specialty ultra-high-strength grades including AerMet 100.
Jiangyin sits in the Yangtze River delta forging cluster in southern Jiangsu, within short road distance of the Zhangjiagang and Shanghai port areas, which keeps lead time and freight cost down on export orders. We work to customer drawings and specifications rather than a fixed catalogue, and supply full material traceability with every shipment. Enquiries in English or Chinese are welcome.
- Company
- Jiangyin Jiangnan Metal Co., Ltd., open-die forging factory
- Address
- No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
- Telephone
- +86-189-2135-9659 (also WhatsApp / WeChat)
- sales@steelforgepieces.com
- Product scope
- Open-die forgings and seamless rolled rings: rings, shafts, discs, blocks, sleeves, flanges, bars
- Materials
- Carbon steel, alloy steel, tool steel, stainless steel, nickel alloys, AerMet 100 and other ultra-high-strength grades
- Certification
- EN 10204 3.1 standard, EN 10204 3.2 third-party on request
Need AerMet 100 Forgings?
Send the drawing, the size list, or simply the finished dimensions and quantity. Tell us the specification, delivery condition and NDT class you need, and we will come back with price and lead time.
Contact Us & Request a Quote →Trademark notice. AerMet® is a registered trademark of CRS Holdings LLC, a subsidiary of Carpenter Technology Corporation. Jiangyin Jiangnan Metal Co., Ltd. is an independent open-die forging house and is not affiliated with, endorsed by, or a licensee of Carpenter Technology Corporation. Grade names are used solely to identify the material specification of the forgings we supply.
Data sources. Composition, mechanical, physical, heat-treatment and forging data on this page are drawn from the Carpenter Technology AerMet® 100 alloy datasheet and from AMS 6532 / AMS 6478. Values shown are typical or nominal and are not a guarantee of maximum or minimum values for any particular heat. Confirm the properties required for your application against the governing specification and your own qualification testing.
Page last reviewed: by Jiangyin Jiangnan Metal Co., Ltd.