AerMet 100 Steel
A Co-Ni-Cr-Mo ultra-high-strength steel
Typical values for the temper in the title
AerMet 100 is a Carpenter steel with about 13.4% cobalt, 11.1% nickel, 3.1% chromium, 1.2% molybdenum and 0.23% carbon. It combines very high strength (yield about 1720 MPa) with much higher fracture toughness than 300M (KIC about 126 MPa√m), and better stress corrosion resistance.
That is why it was chosen for US Navy aircraft landing gear, where the marine environment increases the risk of stress corrosion cracking. Per the producer it may be considered for use up to about 427 °C. The cost: it is very expensive, because of the cobalt and nickel.
Mechanical and physical properties
| Property | Value | Note |
|---|---|---|
| Tensile strength Rm | 1965 MPa | |
| Yield strength Rp0.2 | 1725 MPa | |
| Elongation A | 14% | |
| Modulus of elasticity E | 196 GPa | |
| Density ρ | 7.89 g/cm³ | |
| Hardness | 53–54 HRC (aged) | depends on heat treatment |
| Machinability | 40% | relative rating in the site database |
Chemical composition (wt %)
| Element | Range | Role |
|---|---|---|
| Co cobalt | about 13.4 (nominal) | strength and toughness |
| Ni nickel | about 11.1 (nominal) | toughness |
| Cr chromium | about 3.1 (nominal) | strengthening carbides |
| Mo molybdenum | about 1.2 (nominal) | strengthening particles |
| C carbon | about 0.23 (nominal) | strength |
| Fe iron | balance |
Nominal composition per Carpenter. This is a Carpenter proprietary steel.
Conditions and heat treatment
In alloy steels, chromium, molybdenum and nickel raise hardenability: thicker parts reach full hardness even at the center. Properties are set mainly by heat treatment.
| Condition | Properties | When to choose it |
|---|---|---|
| Annealed / solution treated | for machining | delivery condition |
| Hardened and aged (about 482 °C) | yield about 1720 MPa, 53–54 HRC | finished parts |
Applications
- Naval aircraft landing gear
- High-strength aerospace structural parts
- Defense parts
- Critical shafts
- High-strength tooling
Fabrication
Heat treatment
Solution treat, cool (sometimes deep cool) and age, per the producer specification.
Welding
Possible under controlled conditions, by procedure.
Corrosion
Not stainless: protection is needed, but good stress corrosion resistance compared with 300M.
Compared with similar materials
| Material | Rm / Rp0.2 | Welding | When it is the better choice |
|---|---|---|---|
| 300M | 1930 / 1690 MPa | Very difficult | much cheaper, less tough · material page |
| Maraging 300 | 2050 / 2000 MPa | Excellent | similar strength, excellent dimensional stability in treatment · material page |
| 4340 | 1080–1470 / 970–1380 MPa | Difficult — Preheat 200C | much cheaper, lower strength · material page |
Common mistakes
Choosing AerMet 100 where 300M is enough
The price difference is very large. The choice is justified when toughness and stress corrosion resistance are critical.
Assuming it is stainless
It needs corrosion protection.
Departing from the heat-treatment procedure
Properties are sensitive to treatment. Follow the producer specification.
Equivalents, standards and supply
| AMS | 6532 |
|---|---|
| UNS | K92580 |
| Standards | AMS 6532 |
| Forms | plate · rod · forging |
| Producers | Carpenter Technology |
Learn more
Values are typical and for comparison only, and depend strongly on condition and diameter. For design, rely on the standard and on the mill certificate. Sources: SAE J403 and J404, ASTM A29, A322 and A519 (composition), producer data sheets, and the METAL HUB materials database.
Updated: October 31, 2026