⚡ Quick Specs: Haynes 242
What Is Haynes 242?
Haynes 242 (UNS N10242 / W.Nr. 2.4618) is an age-hardenable nickel-molybdenum-chromium superalloy developed by Haynes International. Unlike precipitation-hardened grades such as Inconel 718 that rely on gamma-prime (γ′) and gamma-double-prime (γ″) phases, Haynes 242 derives its high strength from a unique long-range-ordering reaction. During aging, ordered Ni2(Mo,Cr) domains form coherently in the matrix, essentially doubling the un-aged strength while preserving excellent ductility, impact toughness, and thermal stability.
The alloy was engineered for gas turbine components that must maintain tight clearances at high temperature. Its combination of high creep resistance to 705 °C, low thermal expansion, and very good oxidation resistance to 815 °C makes it the material of choice for seal rings, containment rings, duct segments, casings, and fasteners in aero and industrial gas turbines. As a Haynes 242 manufacturer and supplier, Hangbo Alloy Group supplies the grade in plate, sheet, bar, forging, and ring forms with full mill certification.
Chemical Composition
Nominal composition of Haynes 242 per AMS 5957 / AMS 5958. All values in weight percent (wt%).
| Element | Haynes 242 (wt%) |
|---|---|
| Ni | Balance (62.0 – 65.0) |
| Mo | 24.0 – 26.0 |
| Cr | 7.5 – 8.5 |
| Fe | ≤ 2.0 |
| C | ≤ 0.03 |
| Mn | ≤ 0.80 |
| Si | ≤ 0.80 |
| Co | ≤ 2.5 |
| Al | ≤ 0.50 |
| B | ≤ 0.006 |
| Cu | ≤ 0.50 |
| P | ≤ 0.030 |
| S | ≤ 0.015 |
The 24–26% molybdenum level provides both solid-solution strengthening and resistance to reducing acids, while the 7.5–8.5% chromium contributes oxidation resistance. Low carbon, iron, and silicon are tightly controlled to preserve the long-range-ordered structure and to maintain ductility after long-term thermal exposure.
Physical Properties
| Property | Value |
|---|---|
| Density | 8.17 g/cm³ (0.295 lb/in³) |
| Melting Range | 1237 – 1277 °C (2259 – 2331 °F) |
| Specific Heat (20 °C) | ~ 380 J/kg·K |
| Thermal Conductivity (20 °C) | ~ 11.0 W/m·K |
| Electrical Resistivity (20 °C) | ~ 1.30 µΩ·m |
| Young's Modulus (room temp) | ~ 220 GPa |
| Mean CTE (20–650 °C) | ~ 11.5 × 10⁻⁶ /K |
Mechanical Properties
Typical room-temperature tensile properties after standard solution anneal and age.
| Property | Annealed | Annealed + Aged |
|---|---|---|
| Tensile Strength (Rm) | ~ 690 MPa (100 ksi) | 1100 – 1250 MPa (160 – 181 ksi) |
| Yield Strength (Rp0.2) | ~ 310 MPa (45 ksi) | 750 – 950 MPa (109 – 138 ksi) |
| Elongation (A%) | ≥ 40% | 20 – 30% |
| Hardness | ~ 90 HRB | 28 – 36 HRC |
Haynes 242 retains excellent ductility and impact strength after aging — a direct benefit of the ordered-domain strengthening mechanism. Even after 4000 hours of exposure at 650 °C, aged 242 maintains retained room-temperature elongation and impact values well above those of comparable precipitation-hardened alloys.
High-Temperature Performance
- Creep and stress-rupture: Haynes 242 exhibits creep strength up to 705 °C that is roughly double that of solid-solution-strengthened alloys such as Hastelloy X or Inconel 625.
- Tensile strength at 760 °C: Aged bar and sheet still show tensile strength around 620 MPa, enabling structural load-bearing at very high temperatures.
- Oxidation resistance: Very good oxidation resistance in air to 815 °C, with a protective Cr2O3 scale.
- Thermal stability: The ordered phase remains stable during long-term exposure; no harmful topologically close-packed (TCP) phases form under normal service conditions.
- Low-cycle fatigue: Excellent resistance to thermal and mechanical cycling, important for seal rings and containment hardware.
Corrosion Resistance
Haynes 242 offers a corrosion portfolio driven by its high molybdenum and controlled chromium levels:
- Reducing acids: Excellent resistance to hydrofluoric acid vapor and hydrochloric acid at moderate temperatures.
- Sulfuric acid: Good performance in dilute to moderately concentrated H2SO4.
- High-temperature gases: Very good oxidation and carburization resistance in combustion atmospheres to 815 °C.
- Chloride service: Moderate; for severe chloride pitting or seawater, Inconel 625 or Hastelloy C-276 are generally preferred.
Applications
Haynes 242 is specified wherever high-temperature strength, dimensional stability, and oxidation resistance must coexist. Typical uses include:
| Application Area | Typical Components & Notes |
|---|---|
| Aero Gas Turbines | Seal rings, containment rings, duct segments, casings, and shrouds where low thermal expansion controls clearance |
| Industrial Gas Turbines | Combustor rings, transition pieces, and stationary structural hardware |
| Rocket Propulsion | Nozzle components, thrust chambers, and valve bodies exposed to hot combustion gases |
| Fasteners & Bolting | High-temperature bolting for turbine assemblies requiring stress relaxation resistance |
| Chemical Processing | Pumps, valves, and hydrofluoric acid vapor handling equipment |
| Power Generation | Hot-gas-path components in advanced turbines and energy-recovery systems |
Available Product Forms
| Product Form | Typical Dimensions |
|---|---|
| Sheet & Strip (AMS 5957 / ASTM B434) | Thickness 0.5 – 4.0 mm, width up to 1500 mm |
| Plate (AMS 5957 / ASTM B434) | Thickness 4 – 50 mm, width up to 2500 mm |
| Bar & Rod (AMS 5958) | φ 6 – φ 250 mm, hot-rolled, forged, or cold-drawn |
| Forgings & Rings (AMS 5958) | Seal rings, containment rings, and casings up to 2000 mm OD |
| Wire & Welding Consumables | Matching filler metals for GTAW/GMAW repair and fabrication |
Heat Treatment
| Step | Temperature | Cooling | Purpose |
|---|---|---|---|
| Solution Anneal | 1066 – 1100 °C (1950 – 2012 °F) | Air or water quench | Dissolve ordered phase; soften for forming and machining |
| Aging | ~ 650 °C (1200 °F) | Air cool | Develop ordered Ni₂(Mo,Cr) domains; maximize strength |
Parts are typically machined in the annealed condition and aged as a final step. Welded fabrications may require solution annealing after welding, followed by aging, to restore uniform properties.
Related Standards & Specifications
| Standard | Product Scope |
|---|---|
| AMS 5957 | Sheet, strip, and plate |
| AMS 5958 | Bar, forgings, rings, and welding wire |
| ASTM B434 / ASME SB-434 | Ni-Mo-Cr alloy plate, sheet, and strip |
| UNS | N10242 |
| DIN / W.Nr. | 2.4618 |
Frequently Asked Questions (FAQ)
1. What is Haynes 242?
Haynes 242 (UNS N10242 / W.Nr. 2.4618) is an age-hardenable nickel-molybdenum-chromium superalloy that derives its strength from a unique long-range-ordering reaction during aging. It offers a rare combination of high-temperature strength up to 705 °C (1300 °F), low thermal expansion, and excellent oxidation resistance to 815 °C. The alloy is widely used for gas turbine seal rings, containment rings, duct segments, casings, fasteners, and other components where thermal growth must be tightly controlled.
2. What is the chemical composition of Haynes 242?
Nominal Haynes 242 composition (wt%): Ni balance (~62–65%), Mo 24.0–26.0, Cr 7.5–8.5, Fe ≤2.0, C ≤0.03, Mn ≤0.80, Si ≤0.80, Co ≤2.5, Al ≤0.50, B ≤0.006, Cu ≤0.50, P ≤0.030, S ≤0.015. The high molybdenum content provides solid-solution strengthening and corrosion resistance, while the balanced Ni-Mo-Cr system enables the ordered Ni₂(Mo,Cr) precipitates that double the strength during aging without sacrificing ductility.
3. What is the density and melting range of Haynes 242?
Haynes 242 has a density of approximately 8.17 g/cm³ (0.295 lb/in³) and a melting range of about 1237–1277 °C (2259–2331 °F). The relatively low density compared with other high-Mo nickel alloys helps reduce rotating mass in turbine hardware.
4. What are the mechanical properties of Haynes 242?
Typical room-temperature properties after solution annealing and aging: tensile strength 1100–1250 MPa (160–181 ksi), 0.2% yield strength 750–950 MPa (109–138 ksi), elongation 20–30%, hardness 28–36 HRC. In the annealed condition the alloy is much softer and readily formed; aging doubles the strength while retaining good ductility and impact toughness. At 760 °C, aged 242 still exhibits tensile strength around 620 MPa.
5. How does Haynes 242 achieve its age-hardened strength?
Haynes 242 hardens through a long-range-ordering reaction rather than conventional gamma-prime precipitation. During aging at ~650 °C, ordered domains of Ni₂(Mo,Cr) form coherently within the nickel matrix. This ordered structure doubles the un-aged strength with minimal loss of ductility or impact resistance, and it remains stable during long-term exposure to 650–705 °C.
6. What is the maximum service temperature of Haynes 242?
Haynes 242 is suitable for continuous service up to about 705 °C (1300 °F) and intermittent service up to 815 °C (1500 °F) in oxidizing environments. Its oxidation resistance is very good to 815 °C, and it retains useful creep strength and ductility after thousands of hours at 650 °C.
7. Why is low thermal expansion important in Haynes 242?
Haynes 242 has a lower coefficient of thermal expansion than most nickel-base superalloys, which means it grows less when heated. In gas turbine seal rings, containment rings, and casings this minimizes clearance changes between rotating and stationary parts, improves efficiency, reduces rubbing and wear, and lowers thermal stresses during rapid start-up and shut-down cycles.
8. What is the corrosion resistance of Haynes 242?
The high molybdenum content gives Haynes 242 excellent resistance to reducing acids, including hydrofluoric acid vapor, hydrochloric acid, and sulfuric acid at moderate temperatures. It also performs well in oxidizing combustion gases up to 815 °C and resists carburization and thermal shock. The alloy is not primarily a seawater grade; for chloride service, Inconel 625 or Hastelloy C-276 are usually preferred.
9. Can Haynes 242 be welded and machined?
Haynes 242 can be welded by GTAW, GMAW, and resistance welding processes. Matching filler metals and controlled heat input are recommended to preserve corrosion resistance and mechanical properties in the heat-affected zone. In the annealed condition the alloy machines similarly to other Ni-Mo-Cr alloys; rigid setups, sharp carbide or ceramic tools, and slow speeds with positive feeds are recommended. Aging is performed after final machining.
10. What heat treatment is used for Haynes 242?
Standard heat treatment: solution anneal at 1066–1100 °C (1950–2012 °F), followed by rapid cooling (water or air), then age at ~650 °C (1200 °F) for 8–24 hours. The solution anneal dissolves the ordered phase for forming and machining; the aging step develops the long-range-ordered structure that provides the high strength. Components are normally machined in the annealed condition and aged last.
11. What standards apply to Haynes 242?
Haynes 242 is covered by AMS 5957 (sheet, strip, and plate), AMS 5958 (bar, forgings, rings, and welding wire), ASTM B434 (plate, sheet, and strip), and corresponding ASME SB-434 specifications. UNS designation is N10242; DIN/W.Nr. is 2.4618. Material is supplied with full mill test certificates and traceability.
12. What are the typical applications of Haynes 242?
Primary applications include: (1) Gas turbine seal rings and containment rings; (2) Combustor and transition duct segments; (3) Turbine casings and structural rings; (4) High-temperature fasteners and bolting; (5) Rocket engine nozzles and thrust chambers; (6) Valves, pumps, and hydrofluoric acid vapor handling equipment; (7) Thermal-mechanical fatigue critical components in aero and industrial gas turbines.
Need Haynes 242 for Gas Turbine Seals, Rings, or High-Temperature Hardware?
Hangbo Alloy Group is a trusted global manufacturer and supplier of Haynes 242 (UNS N10242 / 2.4618) in plate, sheet, bar, forging, and ring forms. Mill test certificates to EN 10204 3.1, full traceability, and competitive pricing on every order.