HP 9-4-30 LESCALLOY Steel Round Bar, HP 9-4-30 Alloy Steel Rods, Bars(Nickel Cobalt Aircraft Armour)

Product Description

HP 9-4-30 (commercially branded by Latrobe Steel / Carpenter Technology as Lescalloy HP 9-4-30 Vac-Arc; UNS K91283 / K91313) is the underlying alloy chemistry for all the premium aerospace and defense specifications discussed previouslyincluding AMS 6524, BMS-7-182 Type 2, and MM-S-2102.

When sourced directly by its trade name as HP 9-4-30 Lescalloy Steel Round Bars, Rods, and Bars, it represents the pinnacle of high-fracture-toughness, ultra-high-strength metallurgy designed for nickel-cobalt aircraft armor and high-stress structural defense applications.

1. The Chemistry Behind the Performance

The designation "9-4-30" explicitly highlights its key alloy proportions: 9% Nickel, 4% Cobalt, and 0.30% Carbon. The metallurgy is highly calculated:

• Nickel (7.00% 8.00%): Provides deep through-hardening capability and ensures exceptional plane-strain fracture toughness ($K_{Ic}$) to prevent catastrophic shattering under ballistic strike or high-impact shock loads.

• Cobalt (4.00% 5.00%): Acts as a matrix stabilizer. It raises the martensite start ($M_s$) temperature, minimizes the formation of brittle retained austenite, and allows the steel to retain its hardness even when tempered at high temperatures.

• Vacuum Arc Remelting (VAR): The "Vac-Arc" designation guarantees the material has undergone premium consumable electrode vacuum remelting (usually VIM-VAR) to strip away microscopic gases and non-metallic inclusions.

2. Forms of Supply & Delivery Condition

HP 9-4-30 is processed into bars and rods to accommodate heavy machining, forging, and component fabrication:

• Delivery Condition: Most frequently supplied in the Annealed or Normalized & Tempered (N&T) condition. In this state, it exhibits a uniform microstructure with a typical hardness of 30 to 35 HRC, making it readily machinable via conventional milling, turning, and sawing before final hardening.

• Size Range: Round bars and rods are typically available from 0.500 (12.7 mm) precision ground rods up to large 12+ (304 mm) hot-rolled or forged structural bars.

• Surface Condition: Can be ordered as hot-rolled, centerless turned, peeled, or cold-drawn.

• Testing Rigor: Because of its safety-critical applications, these bars are universally subjected to stringent non-destructive testing (NDT), typically certified to ultrasonic standards like MIL-STD-2154 Class A or AMS 2154 Class A to ensure the core is completely free of sub-surface micro-voids.

3. Key Mechanical Milestones (Heat Treated)

Unlike conventional ultra-high-strength steels (like AISI 4340 or 300M) which can become brittle at extreme tensile levels, HP 9-4-30 maintains a rare balance of tensile strength and ductility.

• Ultimate Tensile Strength (UTS): 220,000 240,000 psi (1517 1655 MPa)

• Yield Strength (0.2% Offset): 200,000 psi (1379 MPa) minimum

• Fracture Toughness ($K_{Ic}$): An extraordinary 130 ksiin ($143\text{ MPa}\sqrt{\text{m}}$)significantly outperforming 300M at similar strength levels.

• Excellent Weldability: Unlike most high-strength aircraft steels that are prone to heat-affected zone (HAZ) cracking, HP 9-4-30 can be TIG welded in the annealed or inert gas shielded state using matching chemistry filler wires.

4. Primary Ballistic & Aerospace Applications

• Aircraft Armor Blading & Shielding: Machined armor panels protecting military pilots, cockpit framing, and critical engine shrouds against anti-aircraft explosive fragmentation.

• Heavy Flight Structural Hardware: Helicopter main rotor masts, landing gear truck beams, wing-attachment wing-pivot pins, and high-torque driveshafts.

• Missile & Space Systems: Solid rocket booster structural joining rings, high-pressure gas bottles, and explosive separation bolt housings.