A4-80 Hex Nut

About A4-80 Hex Nut

The A4-80 Hex Nut is an ultra-high-strength, marine-grade metric internal thread fastener engineered for heavy-duty clamping in severely corrosive environments. The alpha-numeric designation "A4-80" explicitly defines its elite material properties and heavy mechanical performance thresholds under the international ISO 3506-2 standard:

• "A4" indicates it is forged from Grade 316 austenitic stainless steel, fortified with 2% to 3% Molybdenum.

• "80" signifies an elevated minimum tensile strength of 800 MPa, achieved through intense strain-hardening during manufacturing.

Featuring a traditional six-sided profile, this heavy-stress nut is designed to mate with matching high-tensile A4-80 bolts or studs to prevent joint separation under extreme high-pressure or heavy structural loads.

Key Features & Design

• Maximum Tensile Performance: The strain-hardened "80" property class provides a 14% increase in tensile strength over standard A4-70 hardware, drastically reducing the risk of thread stripping or shearing.

• Superior Chemical Defences: The molybdenum-enriched alloy provides specialized resistance against pitting, crevice corrosion, and chloride-induced stress cracking in coastal and acidic environments.

• Six-Sided Driving Geometry: Precision-engineered flat sides ensure highly stable tool engagement for maximum torque transmission without rounding the head.

• Anti-Galling Prepped: While high-tensile stainless steel is prone to friction-wear (galling) during high-torque assembly, A4-80 threads are precision-machined to match exact tolerances, though anti-seize lubricants are highly recommended.

Manufacturing & Dimensional Standards

A4-80 hex nuts are precision-machined to match globally recognized metric parameters:

• ISO 4032: The primary international standard for regular hex nuts (Product Grades A and B).

• DIN 934: The classic, widely referenced German industrial standard for standard hex nuts.

• DIN 985 / ISO 10511: High-strength nylon insert lock nut variant ("Nyloc") designed to stop vibration loosening.

• Thread Fitting: Formed to standard metric coarse or metric fine thread pitches with a precision 6H internal thread tolerance class.

Mechanical Property Profile

• Material Matrix: Strain-Hardened Austenitic Stainless Steel (Type 316 / Marine Grade / Acid-Proof).

• Minimum Tensile Strength: 800 MPa (800 N/mm).

• Minimum Yield Strength: Approximately 600 MPa (significantly higher than the 450 MPa yield of A4-70).

• Thermal Performance: Maintains structural stability and high-load capabilities in extreme temperature ranges from sub-zero environments up to 400C.

Target Applications & Industries

• High-Pressure Petrochemical Pipelines: Securing heavy flange joints, valves, and high-pressure pumping manifolds handling volatile fluids.

• Deepsea & Subsea Maritime Infrastructure: Assembling underwater drilling mechanisms, marine exploration rigs, and coastal defence barriers.

• Heavy Chemical & Acid Processing: Fastening mixing tanks, heat exchangers, and industrial filtration arrays exposed to aggressive chemical vapours.

• High-Stress Aerospace & Transport Frameworks: Structural safety joints in marine transport hulls, heavy-load port cranes, and high-vibration manufacturing equipment.