Alloy Steel CPW 492 (Pratt & Whitney Grade) Bars/ CPW 492 Rods / CPW 492 Rings

Product Description

CPW 492 is a high-performance, aerospace-grade alloy steel specification managed by Pratt & Whitney. It is a premium-melted (typically VIM-VAR or VAR) low-alloy steel designed for critical engine components that require high fatigue strength, excellent cleanliness, and superior fracture toughness.

This grade is closely related to the AMS 6414 and AMS 6415 specifications, sharing a chemical profile similar to AISI 4340, but with much stricter controls on impurities and melting practices to meet aerospace standards.

Technical Profile: CPW 492

Chemical Composition (%)

As a "clean" version of 4340, CPW 492 utilizes a nickel-chromium-molybdenum balance to provide deep hardenability and high strength.

Mechanical Properties (Typical Heat Treated)

CPW 492 is prized for its high strength-to-weight ratio and its ability to maintain ductility even at high hardness levels.

• Tensile Strength: 1,240 a 1,515+ MPa (180 a 220+ ksi)

• Yield Strength: 1,100 a 1,310 MPa (160 a 190 ksi)

• Hardness: Typically 36 a 45 HRC (depending on tempering temperature)

• Fracture Toughness ($K_{IC}$): Significantly higher than standard 4340 due to vacuum arc remelting (VAR).

Key Characteristics

• Deep Hardenability: The nickel and chromium content ensures that even large cross-sections (like heavy bars or thick rings) achieve uniform hardness from surface to core.

• Cleanliness: Under Pratt & Whitneya s CPW 492 specification, the material must undergo stringent inclusion rating tests. The removal of non-metallic inclusions is vital for preventing fatigue failure in rotating engine parts.

• Fatigue Resistance: Specifically engineered to withstand the cyclic loading and high-stress environments found in jet engines.

• Machinability: In the annealed state, it is manageable; however, it is often machined in the normalized or tempered condition to ensure dimensional stability.

Applications by Form

Pratt & Whitney utilizes CPW 492 for components where failure is not an option:

• Bars and Rods: Used for high-strength fasteners, transmission shafts, and structural connectors in the engine nacelle or core.

• Rings (Seamless/Forged): Used for bearing races, spacers, and structural engine rings. These are often produced via ring rolling to ensure a circumferential grain flow, which maximizes strength.

• Gears and Shafting: Critical power transmission components that require the high surface hardness provided by nitriding or induction hardening (which this grade responds to very well).

Supply Condition & Specifications