Nimonic 90A Superalloy | N07090 | 2.4632 | VIM VAR PESR | Fushun Metal

Nimonic 90A / N07090 / 2.4632 — Introduction

Nimonic 90A, designated UNS N07090 and Werkstoff Nr. 2.4632, is a precipitation-hardenable nickel-chromium-cobalt superalloy strengthened by additions of titanium and aluminum. Originally developed by Henry Wiggin (now part of Special Metals), it delivers exceptional stress-rupture strength and creep resistance at temperatures up to 920°C, paired with outstanding oxidation and corrosion resistance in the 815–870°C range. The alloy derives its high-temperature performance from approximately 18–22 vol.% gamma-prime (Ni₃(Al,Ti)) precipitates, reinforced by solid-solution hardening from a nominal 18% cobalt content that raises the gamma-prime solvus temperature and promotes a dense, thermally stable precipitate distribution throughout long-term service.

At Fushun Metal, Nimonic 90A is manufactured through a fully integrated triple-melt route under one roof. VIM primary melting under high vacuum prevents oxidation of the reactive precipitation-strengthening elements—aluminum and titanium—whose precise recovery is essential to achieving the target gamma-prime volume fraction. The VIM electrode then passes through VAR, where controlled directional solidification in a water-cooled copper crucible eliminates macro-segregation and yields the chemically homogeneous, low-inclusion microstructure demanded by aerospace rotating-component specifications. For applications requiring maximum sulfide cleanliness and isotropic transverse properties—such as bolting and spring wire—we deploy PESR as the final stage, delivering deep desulfurization through reactive slag chemistry under inert gas shielding.

Every heat is processed, forged, heat-treated, and tested within Fushun Metal’s certified quality management system—ISO 9001 for manufacturing process control and AS9120B for aerospace distribution traceability. From initial charge preparation through to the final mill test certificate, each production lot carries full digital traceability linked to melt heat number, remelt sequence, forging reduction ratio, and heat treatment batch. Ultrasonic inspection per AMS 2375, dye-penetrant testing, mechanical test coupons, and chemical re-verification by optical emission and LECO combustion analysis are standard on every shipment.

Equivalent Grades of Nimonic 90A Across International Standards

Nimonic 90A is codified under multiple national and international specification systems. The table below maps its designations and governing standards across major markets. Fushun Metal certifies to all listed specifications and can dual-certify heats where required.

Applications of Nimonic 90A

Nimonic 90A is specified wherever high creep-rupture life, fatigue strength, and oxidation resistance must be maintained simultaneously in the 650–920°C range. Its high gamma-prime volume fraction and excellent hot-hardness retention make it the alloy of choice for rotating and dynamically loaded hot-end components across aerospace, power generation, and high-performance automotive sectors.

Nimonic 90A — Supply Range by Fushun Metal

Fushun Metal stocks and processes Nimonic 90A across all major mill forms from a single integrated facility. Our in-house 6000-ton hydraulic open-die press, 1800-ton precision radial forger (GFM), and multi-stand 850/550/350/250 rolling mills enable a broad dimensional envelope without outsourcing—ensuring uninterrupted lot traceability from melt to delivery under ISO 9001 and AS9120B. Material is supplied in the solution-annealed condition per BS HR 1 / AMS 5829, ready for machining, forming, or subsequent precipitation hardening by the customer. All forged products are ultrasonic tested to AMS 2375 Class A and accompanied by mill test certificates to EN 10204 3.1 or 3.2 as required.

Chemical Composition of Nimonic 90A — BS HR 1 / AMS 5829

All heats produced by Fushun Metal are melted via VIM+VAR or VIM+PESR and verified against the composition limits below by optical emission spectrometry and LECO combustion analysis. Full chemical certificates are issued with every shipment under ISO 9001 and AS9120B quality management. The tightly controlled aluminum-to-titanium ratio and the nominal 18% cobalt content are critical—cobalt raises the gamma-prime solvus temperature to approximately 985–1010°C, directly governing the maximum service temperature and long-term microstructural stability of the alloy.

Mechanical Properties of Nimonic 90A — Per Product Form

The values below represent minimum guaranteed properties in the fully heat-treated condition: solution treatment at 1080°C ± 10°C (rapid air or oil quench), followed by precipitation aging at 700°C ± 10°C for 16 hours (air cool), per AMS 5829 / BS HR 1. This standard heat treatment cycle produces the optimal balance of room-temperature tensile strength, elevated-temperature creep-rupture life, and ductility for rotating and dynamically loaded hot-end components.

Fushun Metal performs all heat treatment in-house under calibrated furnace controls and Nadcap-compliant procedures. For spring-temper wire applications requiring maximum fatigue life in service up to 550°C, an alternative aging schedule of 750°C for 4 hours (air cool) can be applied. Material can be supplied in the solution-annealed condition for customer-side forming and subsequent precipitation hardening, or in the fully aged condition ready for finish machining.

Physical constants: Density 8.18 g/cm³; Melting range 1335–1370°C; Hardness 248–311 HB (aged condition); Modulus of elasticity 213 GPa at 20°C; Thermal conductivity 11.7 W/m·K at 20°C; Coefficient of thermal expansion 12.3 μm/m·°C (20–100°C). The alloy is essentially non-magnetic in the annealed and aged conditions.