EMS 35 (Timken Grade For Aerospace) Bars/ EMS 35 Rods / EMS 35 Rings

Product Description

EMS 35 is a high-strength, premium-quality alloy steel specification developed by TimkenSteel (formerly Timken) specifically for the aerospace industry. It belongs to the Nickel-Chromium-Molybdenum (Ni-Cr-Mo) family of steels and is often cross-referenced with AMS 6414 or AISI 4340 (Vacuum Arc Remelted).

Because it is an EMS (Engineering Material Specification) grade, it is produced to extremely tight metallurgical tolerances, ensuring the cleanliness and structural integrity required for critical flight-safety components.

Technical Profile: EMS 35

Chemical Composition (%)

The chemistry is designed for deep through-hardening, allowing large-diameter bars and rings to maintain uniform properties from the surface to the center.

Mechanical Properties (Typical)

EMS 35 is generally used in the heat-treated condition (Quenched and Tempered) to achieve an optimum balance of ductility and high tensile strength.

• Tensile Strength: 1,240 a 1,550 MPa (180 a 225 ksi)

• Yield Strength: 1,100 a 1,380 MPa (160 a 200 ksi)

• Hardness: 36 a 45 HRC (typical, can be adjusted via tempering)

• Impact Toughness: High Charpy V-notch values even at cryogenic temperatures, essential for aerospace environments.

Key Characteristics

• VAR Melting: EMS 35 is typically Vacuum Arc Remelted (VAR). This process eliminates dissolved gases and minimizes non-metallic inclusions, which is critical for preventing fatigue failure.

• Isotropic Properties: Due to its extreme cleanliness, the difference between longitudinal and transverse mechanical properties is minimized.

• Deep Hardenability: The alloy's composition allows it to harden effectively even in heavy sections, making it ideal for large-scale forgings.

• Fatigue Resistance: Specifically designed to resist the initiation of cracks under cyclic loading.

Applications by Form

• EMS 35 Bars and Rods:

  • Landing Gear Components: Specifically axles, struts, and shock absorbers.

  • High-Torque Shafting: Power transmission shafts in both fixed-wing aircraft and helicopters.

  • Structural Fasteners: Large-diameter bolts and studs used in airframes.

• EMS 35 Rings:

  • Engine Housings: Forged and rolled rings used in jet engine compressor stages.

  • Bearing Races: High-fatigue bearing assemblies for rotating aerospace machinery.

  • Structural Flanges: Connecting points for pressurized sections of aircraft.

Specifications & Material Standards

Fabrication & Heat Treatment

EMS 35 is usually supplied in the annealed condition for ease of machining. For final application, it undergoes:

1. Austenitizing: Heating to approximately $815A \text{C} a 845A \text{C}$.

2. Quenching: Typically in oil to prevent cracking while ensuring a fully martensitic structure.

3. Tempering: At temperatures above $200A \text{C}$ to reach the target hardness. Note: Tempering between $260A \text{C}$ and $370A \text{C}$ is generally avoided to prevent "tempered martensite embrittlement."