Overview
Nimonic 80A (Russian designation ХН77ТЮР or ЭИ437Б, Chinese designation GH4033) is a precipitation-hardenable nickel-chromium superalloy strengthened by gamma prime (γ') phase — Ni₃(Al,Ti). With excellent creep resistance and oxidation resistance up to 750°C, it is widely used in gas turbine blades, discs, and high-temperature fasteners in aerospace and industrial gas turbine applications.
Chemical Composition
| Element | Nimonic 80A / ХН77ТЮР |
|---|---|
| Nickel (Ni) | Balance (~77%) |
| Chromium (Cr) | 19.0–22.0% |
| Titanium (Ti) | 2.0–2.8% |
| Aluminum (Al) | 0.6–1.0% |
| Carbon (C) | ≤ 0.07% |
| Manganese (Mn) | ≤ 0.4% |
| Silicon (Si) | ≤ 0.6% |
| Boron (B) | ≤ 0.01% |
| Cerium (Ce) | ≤ 0.01% |
Titanium and aluminum are the key precipitation-hardening elements, forming the coherent γ' strengthening phase Ni₃(Al,Ti) during aging treatment.
Mechanical Properties
| Property | 20°C | 700°C |
|---|---|---|
| Tensile Strength (Rm) | ≥ 900 MPa | ≥ 600 MPa |
| Yield Strength (Rp0.2) | ≥ 650 MPa | 400–450 MPa |
| Elongation (A) | ≥ 15% | ≥ 8% |
| Density | 8.19 g/cm³ | |
Creep Properties
- 100-hour creep rupture strength at 700°C: σ₁₀₀ ≈ 200–250 MPa
- 10,000-hour creep rupture strength at 700°C: σ₁₀₀₀₀ ≈ 120–150 MPa
- 100-hour rupture strength at 750°C: σ₁₀₀ ≈ 150 MPa
These properties limit continuous service above 750°C. For higher temperature requirements, Nimonic 90 or Inconel 718 should be considered.
Heat Treatment (Precipitation Hardening)
- Solution Treatment: 1080±10°C, hold 8 hours, air cool
- First Stage Aging: 750±10°C, hold 16 hours, air cool
- Second Stage Aging: 700±10°C, hold 16 hours, air cool
The two-stage aging process optimizes the size and distribution of γ' precipitates for maximum creep resistance.
International Standards
| Standard | Designation |
|---|---|
| GOST (Russia) | ХН77ТЮР / ЭИ437Б |
| GB (China) | GH4033 |
| ASTM | B637 (bar/forging) |
| British Standard | Nimonic 80A |
| DIN/EN | 2.4631 |
Aerospace & Gas Turbine Applications
- Low-pressure turbine blades — service to 750°C
- Turbine discs — compressor and turbine rotor components
- Sealing ring elements — hot section static seals
- Fasteners — bolts, studs for temperatures up to 700°C
- Combustion chamber components
- Nozzle guide vanes
Comparison with Nimonic 80A
ХН77ТЮР and Nimonic 80A are essentially identical in chemical composition and mechanical properties. Minor differences: Nimonic 80A may have tighter control on boron (B ≤ 0.008%) and may include zirconium (Zr ≤ 0.05%). For practical purposes, these grades are interchangeable.