MK-84 2000 lb Bomb Casing, forged to 880+ MPa yield.

1. Introduction

The MK-84 2000 lb Bomb Casing is the hardened steel shell for the U.S. Mark 84 general-purpose aerial bomb, the largest in the 1,000-series family introduced during the Vietnam War. With a nominal weight of 2,000 lb (actual weight 1,972–2,028 lb depending on fin and fuze configuration), the casing is sized to house approximately 945 lb of high-explosive fill — typically Tritonal or PBXN-109 — enabling a crater up to 50 ft wide and 36 ft deep upon detonation once filled, fuzed, and armed by the customer. The casing's low-drag, streamlined profile and precise machining ensure compatibility with both unguided delivery and a variety of precision-guidance kits (e.g. Paveway, JDAM).

2. Key Features

• High-strength alloy construction: forged and heat-treated 40Ni6Cr4Mo3 steel provides a tensile strength of 1,100–1,250 MPa and Vickers hardness of 352–375 HV, balancing toughness and resistance to in-service stresses.
• Aerodynamic, low-drag design: smooth, burr-free outer profile with flow-direction machining minimizes drag for stable, predictable ballistic performance.
• Modular compatibility: six equispaced 7 mm slots and four M12 × 1.75P tapped holes on a 290 mm PCD allow attachment of tail fins, guidance strakes, or handling fixtures — supporting variants from free-fall configurations to guided munitions.
• Full traceability & QA: each forging batch is accompanied by NABL-accredited chemical and mechanical test certificates; independent on-site sampling and testing are conducted if certificates are missing or incomplete.

3. Technical Specifications

4. Applications

• Unguided GP bombs: standard free-fall ordnance for area suppression.
• Laser-guided munitions (Paveway series): integration of laser seeker kits for pinpoint strikes under clear-sky conditions.
• GPS/INS-guided munitions (JDAM): retrofittable tail-kits transform the casing into all-weather "smart" bomb configurations with CEP < 30 ft.
• Sea mines (Quickstrike): conversion into rapid-deployment naval mines.
• Bunker-penetrating warheads: fitted with hardened nose plugs for deep concrete penetration.

5. Mechanical & Metallurgical Requirements

• Ultimate tensile strength: 1,100–1,250 MPa.
• Yield strength: ≥ 880 MPa.
• Elongation at break: ≥ 11%.
• Hardness (Vickers): 352–375 HV.
• Forging & flow forming: grain-flow orientation along the axis achieved via controlled multi-stage forging and/or flow-forming processes, enhancing fatigue resistance.
• Heat treatment: quench and temper cycles precisely controlled to develop the required microstructure (tempered martensite) and avoid quench cracks.

6. Non-Destructive Testing

• Ultrasonic testing (ASTM A388): detection of internal discontinuities; flat-bottom hole (FBH) indications ≤ 1.2 mm accepted; reject on loss of back-reflection or < 10% FSH.
• Magnetic particle testing (IS 3703:2004): surface crack detection using head-tailstock or central conductor methods; zero tolerance for surface defects; full demagnetization post-test.
• Radiography (MIL-STD 2154, where required): verification of wall thickness uniformity and internal voids in high-stress regions.

7. Component Inspection & Scope of Supply

• Incoming material inspection: review of NABL certificates; random sampling for mechanical, chemical, and NDT verification if documentation is inadequate.
• Dimensional control: coordinate-measuring machines (CMMs) verify all critical dimensions (slots, holes, chamfers) against the approved drawing; results logged and retained for traceability.
• Gauge calibration: all inspection tools calibrated to national standards; calibration dates and operator IDs recorded.
• Quality assurance sign-off: a formal release board signs off on every lot, confirming compliance with delivery-period and specification requirements.
• Scope boundary: Neometrix's supply ends at the forged, machined, inspected casing. Explosive filling, fuzewell closure, nose-plug fitting, arming, and final assembly are performed separately by the customer's ordnance facility.

Conclusion

The MK-84 2000 lb Bomb Casing combines proven aerodynamics, modular attachment features, and stringent metallurgical standards to deliver a shell body of exceptional reliability. Its traceable, high-strength alloy construction and rigorous NDT regime give ordnance factories a consistent, certified casing for downstream explosive filling and assembly — from legacy free-fall configurations to precision-guided variants.