Nimonic 263/UNS N07263/W. Nr. 2.4650/Alloy 263 bar

Nimonic 263 bar, designated as UNS N07263 and material number W.Nr. 2.4650, is a nickel-chromium-cobalt-molybdenum superalloy strengthened by precipitation hardening with titanium and aluminum. It is specifically engineered for excellent fabricability, weldability, and high-temperature strength, particularly in sheet metal and fabricated assemblies for gas turbine engines. This bar stock form provides the necessary material for machining components such as combustion chambers, casings, afterburner liners, and high-temperature ducting where a combination of good creep strength and ease of welding is required at temperatures up to approximately 850°C (1560°F).

Introduction to Nimonic 263 (Alloy 263)

Nimonic 263 was developed to address the need for a readily fabricable, weldable sheet and bar alloy with properties superior to older alloys like Nimonic 75 but without the severe fabrication challenges of some higher-strength grades. Its balanced composition provides a good compromise between strength, ductility, and oxidation resistance, making it particularly suitable for complex fabricated structures in the aerospace and power generation industries. The bar stock is often used for machining rings, flanges, and supports that are subsequently welded into larger assemblies.

Chemical Composition of Nimonic 263 Bar

The properties of Nimonic 263 bar are derived from a composition optimized for weldability and stable high-temperature performance. Supplied by Shanghai NC Metal Materials Co., Ltd., the bar stock meets aerospace specifications that emphasize these characteristics.

Mechanical Properties of Nimonic 263 Bar (Heat Treated)

Nimonic 263 bar is used in the precipitation-hardened condition. Its strength is developed through a two-stage heat treatment process.

Typical Value (Aged Condition)

Physical Properties of Nimonic 263 Bar

The physical properties of Alloy 263 are important for the design of thermally cycled components.

Notes / Condition

Standard Specifications, Bar Forms, and Available Sizes

Shanghai NC Metal Materials Co., Ltd. supplies Nimonic 263 bar primarily for aerospace fabrication, often as a complement to sheet and plate products.

Primary Applications of Nimonic 263 Bar Stock

Machined components from Nimonic 263 bar are typically integrated into larger welded structures for high-temperature service: Aerospace Gas Turbines: Combustion chamber casings, afterburner liners, transition ducts, exhaust assemblies, and support rings. These are often fabricated from sheet with bar stock used for machined flanges and attachments. Industrial Gas Turbines: Combustor cans, transition pieces, and hot gas path ducting. Rocket Engine Components: Combustion chambers and nozzles where weldability is key. High-Temperature Fabrications: Any complex welded assembly requiring good strength and oxidation resistance up to 850°C.

Heat Treatment

Nimonic 263 utilizes a specific two-stage heat treatment for optimal properties: Solution Treatment: Typically at 1150°C (2100°F), followed by rapid cooling (air quench). This dissolves the γ’ phase. Aging Treatment: A two-step aging process is standard: first at 800°C (1470°F) for 8 hours, air cool, then at 700°C (1290°F) for 8 hours, air cool. This carefully controlled precipitation develops a stable microstructure with a good balance of strength and ductility, which is crucial for weldability and thermal fatigue resistance in fabricated structures.

Machining and Fabrication

Machining Nimonic 263 bar is performed in the solution-annealed condition. It is a tough, work-hardening alloy but is generally more machinable than higher-strength rotor-grade superalloys. Standard practices for nickel alloys apply: rigid setups, sharp positive-rake carbide tools, moderate speeds and feeds, and good coolant. Its excellent formability in the annealed condition allows for cold bending and shaping of bar into rings or other forms before aging. This fabricability is a key design feature.

Welding Characteristics (Key Advantage)

Nimonic 263 is renowned for its excellent weldability among precipitation-hardened superalloys. This is due to its controlled aluminum content and carbon level, which minimize susceptibility to strain-age cracking and liquation cracking. It can be welded using Gas Tungsten Arc Welding (GTAW/TIG), Plasma Arc Welding (PAW), and Electron Beam Welding (EBW) without preheat. Matching filler metals (e.g., ERNiCrCoMo-1) are used. A full post-weld heat treatment (solution treat + age) is recommended for optimal properties, but for many sheet metal fabrications, a simple post-weld aging treatment can be sufficient, which is a significant fabrication advantage.

Reference Pricing and Key Purchasing Factors

The price of Nimonic 263 bar from Shanghai NC Metal Materials Co., Ltd. is influenced by its cobalt and molybdenum content and its position as a premium fabricable sheet/bar alloy.