HN77TYUR (EI437B) — Russian Equivalent of Nimonic 80A
HN77TYUR (old designation EI437B) is the Russian precipitation-hardening nickel-chromium alloy that is equivalent to Nimonic 80A (Chinese GH4033). It was one of the first commercial superalloys strengthened by gamma prime (γ') precipitation of Ni₃(Al,Ti) and remains widely used for gas-turbine blades, discs and bolts requiring strength and oxidation resistance up to about 750°C. This article covers its composition, properties, heat treatment and applications.
1. Chemical Composition
| Element | HN77TYUR / Nimonic 80A |
|---|---|
| Ni | Balance |
| Cr | 19.0–22.0 |
| Ti | 2.40–2.80 |
| Al | 1.00–1.80 |
| Fe | ≤1.0 |
| Mn | ≤0.40 |
| Si | ≤0.80 |
| C | ≤0.10 |
The combined titanium and aluminium content (about 3.4–4.6%) forms the coherent gamma prime (γ') precipitate that gives the alloy its high strength.
2. Mechanical Properties (Hardened)
| Property | Typical Value |
|---|---|
| Yield strength σ₀.₂, MPa | 600–700 |
| Tensile strength σᵦ, MPa | 1000–1150 |
| Elongation, % | 20–30 |
| Service temperature | up to ~750–800°C |
3. Strengthening Mechanism
Nimonic 80A / HN77TYUR is strengthened by the precipitation of gamma prime (γ'), Ni₃(Al,Ti), a coherent, ordered phase that obstructs dislocation motion. The chromium provides oxidation and corrosion resistance, while the Ti/Al drives strength.
4. Heat Treatment
| Step | Typical Condition |
|---|---|
| Solution treatment | ~1080°C, air cool |
| Aging | ~700°C, hold, air cool |
Solution treatment dissolves the gamma prime; aging reprecipitates it as a fine, strengthening dispersion.
5. Applications
| Industry | Typical Components |
|---|---|
| Aerospace / gas turbines | Blades, discs, bolts, rings |
| Industrial turbines | Blades, fasteners |
| High-temp bolting | Studs, nuts to ~750°C |
6. Weldability
This alloy is weldable but less forgiving than Inconel 718 because its gamma-prime strengthening is sensitive to strain-age cracking. Welding is done with matching nickel alloy filler, and post-weld heat treatment is often needed to restore full properties.
7. Standards and Equivalents
| System | Designation |
|---|---|
| UNS / Nimonic | N07080 (Nimonic 80A) |
| Russian (GOST) | HN77TYUR, EI437B |
| Chinese (GB) | GH4033 |
| BS / AMS | HR1/HR201, AMS 5766 |
8. Conclusion
Need Nimonic 80A / GH4033 Forgings or Bars?
Shanghai Hangbo Alloy Group supplies Nimonic 80A (GH4033) forgings, discs, rings and bars equivalent to Russian HN77TYUR / EI437B, with EN 10204 3.1/3.2 certification and full traceability.
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Summary: HN77TYUR (EI437B) and Nimonic 80A (GH4033) are equivalent gamma-prime-strengthened nickel superalloys for turbine blades and high-temperature bolting up to about 750°C. Their Ti/Al chemistry, oxidation-resistant chromium and mature heat-treatment routes make them a proven choice where moderate superalloy strength is required.
9. Frequently Asked Questions (FAQ)
1. What is HN77TYUR and how is it related to Nimonic 80A?
HN77TYUR (EI437B) is the Russian-grade equivalent of Nimonic 80A (GH4033); both are gamma-prime-strengthened nickel-chromium alloys for the same turbine applications.
2. What is its chemical composition?
Ni balance, Cr 19-22, Ti 2.4-2.8, Al 1.0-1.8, Fe ≤1.0, C ≤0.10. The Ti+Al (≈3.4-4.6%) forms gamma prime.
3. What are its mechanical properties?
Hardened: yield 600-700 MPa, tensile 1000-1150 MPa, useful to about 750-800°C.
4. What heat treatment does it use?
Solution at about 1080°C followed by aging at about 700°C to develop gamma prime.
5. What are its main applications?
Gas-turbine blades, discs, bolts and rings up to about 750°C.
6. Is it weldable?
Yes, but sensitive to strain-age cracking; matching nickel filler and often post-weld heat treatment are used.
7. What standards cover it?
Nimonic 80A: BS HR1/HR201, UNS N07080, AMS 5766. Russian HN77TYUR/EI437B (GOST 5632). Chinese GH4033.
8. In what forms is it supplied?
Bar, forged billet, disc, ring and sheet, supplied with EN 10204 3.1/3.2 certification.