Key facts
Where to buy| Property | Value | Source |
|---|---|---|
| Name | MIL-HDBK-5J calls it 5Cr-Mo-V aircraft steel and lists AMS 6487 for it; the title of AMS 6487 names the same chemistry as H-11 | MIL-HDBK-5J, par. 2.4.1.0 and Table 2.4.1.0(b); SAE AMS 6487 title |
| Composition | Chromium about 5 %, molybdenum about 1.3 %, vanadium about 0.5 %, carbon 0.38–0.43 % | SAE AMS 6487 title: 5.0Cr - 1.3Mo - 0.50V (0.38 - 0.43C) (H-11) |
| Temperature range | High strength up to 1,000 °F; air hardenable, little distortion in thick sections | MIL-HDBK-5J, par. 2.4.1.0 and Table 2.4.1.0(b); SAE AMS 6487 title |
| Quality | Consumable electrode vacuum-melted recommended for aerospace | MIL-HDBK-5J, par. 2.4.1.0 and Table 2.4.1.0(b); SAE AMS 6487 title |
| Sheet, strip, plate | AMS 6437 | MIL-HDBK-5J, Table 2.4.1.0(d) |
| Bars and forgings | AMS 6487 and AMS 6488 | MIL-HDBK-5J, Table 2.4.1.0(c) |
| Heat treatment | 1,850 ± 50 °F, hold 15–25 min for sheet or 30–60 min for bar, air cool, temper three times for 2–3 h each, air cool | MIL-HDBK-5J, par. 2.4.1.0 and Table 2.4.1.0(b); SAE AMS 6487 title |
Design allowables — 5Cr-Mo-V sheet, strip and plate, quenched and tempered
AMS 6437, S basis. MIL-HDBK-5J Tables 2.4.1.0(d) and 2.4.1.0(a).
| Property | 240 ksi level | 260 ksi level | 280 ksi level | Unit |
|---|---|---|---|---|
| Ftu, LT | 240 | 260 | 280 | ksi |
| Fty, LT | 200 | 220 | 240 | ksi |
| Fcy, LT | 220 | 240 | 260 | ksi |
| Fsu | 144 | 156 | 168 | ksi |
| Elongation, LT, in 2 in (sheet over 0.050 in) | 6 | 5 | 4 | % |
| Elongation, LT, in 1 in | 8 | 7 | 6 | % |
| Tempering temperature | 1,050 | 1,030 | 1,000 | °F |
| Hardness | 49–52 | 52–54 | 54–56 | HRC |
The tempering and hardness values are from Table 2.4.1.0(a) pages 2-66 and are listed against Ftu levels 280, 260, 240 and 220 ksi at 1,000, 1,030, 1,050 and 1,080 °F. Design values apply only to parts whose Ftu is substantiated by quality control testing. Source: MIL-HDBK-5J, Table 2.4.1.0(d), p. 2-69.
Thicknesses and forms
Forms: sheet, strip and plate (AMS 6437); bars and forgings (AMS 6487, 6488). Bar properties depend on cross-section and on transverse specimen length; read Table 2.4.1.0(c), p. 2-68.
Forming
Sheet is formed soft and then hardened; no bend radius is in the public FAA documents. Dimensional change in the quench is small because the steel hardens in air (MIL-HDBK-5J, par. 2.4.1.0).
Quick check
What is the standout property of H-11 / 5Cr-Mo-V?
- Excellent weldability
Not this one. The handbook gives no welding claim; it stresses air hardening and high-temperature strength.
- High strength to about 1,000 °F with little heat-treat distortion
Best fit. Right. Air hardenability and strength to 1,000 °F (par. 2.4.1.0).
- It is cheaper than 4130
Not this one. Cost is not a handbook property and not the reason it is chosen.
On a real job, the SRM decides.
Welding
The handbook gives no welding guidance for this steel. Welding a hardened part is not a repair method; follow the manufacturer or the SRM.
Corrosion
Protect and treat like other high-strength steels (AC 43.13-1B par. 6-165): mild abrasives only, no chemical removers without engineering authorization.
Where it is used on aircraft
Highly loaded parts that run hot, up to 1,000 °F, at 240–280 ksi. The handbook states the temperature capability and the air-hardening behaviour.
Data sheet
Questions people actually ask
Is H-11 the same as 5Cr-Mo-V?
Same composition family. MIL-HDBK-5J uses the 5Cr-Mo-V name; the spec title on the certificate tells you which name your material carries.
Limits — when NOT to use this
- Vacuum-melted material. The handbook recommends only that quality for aerospace.
- Sheet values only here. Bar values are in Table 2.4.1.0(c).
Where to buy
Distributors coming soon.
Sources
- MIL-HDBK-5J, Metallic Materials and Elements for Aerospace Vehicle Structures (31 Jan 2003) — par. 2.4.1.0; Tables 2.4.1.0(a), (c) and (d), pp. 2-66 to 2-69. Cancelled; superseded by MMPDS.
- FAA AC 43.13-1B CHG 1 — par. 6-165.
- MMPDS (formerly MIL-HDBK-5) — the current home of design allowables. A repair substantiation cites MMPDS or the SRM, not a website.
- SAE AMS 6487K, Steel, Bars, and Forgings 5.0Cr - 1.3Mo - 0.50V (0.38 - 0.43C) (H-11) — Title (the full text is paywalled).