A4-70 Hex Nut

About A4-70 Hex Nut

The A4-70 Hex Nut is a premium, marine-grade metric internal thread fastener engineered for high-strength clamping in highly corrosive and chemically aggressive environments. The alpha-numeric designation "A4-70" explicitly defines its material properties and 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.

• "70" signifies a high minimum tensile strength of 700 MPa, achieved through precise cold-working.

Featuring a traditional six-sided profile, this nut is designed to mate with matching A4-70 bolts, studs, and threaded rods to provide ultra-reliable joint integrity under severe operational stress.

Key Features & Design

• Advanced Pitting Resistance: The molybdenum content prevents pitting, crevice corrosion, and chloride-induced stress cracking caused by saltwater and harsh acids.

• High Torque Retention: The cold-hardened "70" property class allows for high tightening torque without the risk of stripping or deforming the internal threads.

• Six-Sided Driving Geometry: Flat sides provide a broad surface area for secure wrenching, ensuring easy tool engagement using standard metric sockets or spanners.

• Non-Magnetic Properties: Retains an almost entirely non-magnetic structure, making it perfect for sensitive medical, electronic, and scientific hardware.

Manufacturing & Dimensional Standards

A4-70 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: Nylon insert lock nut variant ("Nyloc") designed to resist loosening under severe vibrations.

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

• Minimum Tensile Strength: 700 MPa (700 N/mm).

• Minimum Yield Strength: Approximately 450 MPa.

• Thermal Performance: Maintains structural stability and oxidation resistance in temperatures ranging from sub-zero environments up to 400C.

Target Applications & Industries

• Marine & Offshore Engineering: Securing ship hulls, underwater rig mechanisms, dock installations, and seaside desalination plants.

• Chemical, Oil, & Gas Processing: Joining high-pressure pipelines, chemical mixing vats, heat exchangers, and refinery machinery handling corrosive liquids.

• Wastewater Treatment: Fastening industrial pumps, aeration grids, and sewer filtration structures exposed to harsh biological fluids and chemical additives.

• Pharmaceutical & Food Production: Assembling cleanroom appliances, sanitary storage vessels, and surgical production equipment requiring deep chemical sanitization.