The Stainless Steel Socket Head Cap Screw (also known as a stainless Allen bolt or DIN 912 socket screw) is an essential high-precision fastener engineered for counterbored installations in corrosive, sanitary, and demanding outdoor environments. Manufactured from premium austenitic stainless steel alloys (SS304 / A2-70 and SS316 / A4-80), this fastener forms a self-repairing chromium oxide passive layer that resists pitting corrosion, acid attack, and atmospheric oxidation in accordance with global ISO standards.
Technical Specifications of Stainless Steel Socket Head Cap Screw
Austenitic stainless steel socket cap screws combine high torque capability with non-magnetic and rust-proof physical properties. Grade A2-70 (SS304) provides reliable 700 MPa tensile strength for general machinery, medical, and food-grade equipment. Grade A4-80 (SS316) includes molybdenum addition (2–3% Mo) to achieve 800 MPa tensile strength while resisting aggressive chloride ion pitting in marine and chemical plants.
| Grade Marking | Stainless Material Grade | Tensile Strength (Min) | Proof Stress 0.2% (Min) | Corrosion Environment |
|---|---|---|---|---|
| A2-50 / A2-70 | AISI 304 / SS304 (1.4301 / 06Cr19Ni10) | 500 – 700 N/mm² (700 MPa) | 450 N/mm² (450 MPa) | Freshwater, General Outdoor & Food Processing |
| A4-70 / A4-80 | AISI 316 / SS316 (1.4401 / 06Cr17Ni12Mo2) | 700 – 800 N/mm² (800 MPa) | 600 N/mm² (600 MPa) | Marine Coastal, Salt Spray & Chemical Processing |
Precision Forging and Passivation Process for Stainless Steel Socket Head Cap Screw
At our manufacturing plant in Handan, China, stainless steel socket head screws are cold-forged and chemical-treated to achieve accurate dimensional tolerances and bright aesthetic finish:
- Internal Hex Socket Cold Extrusion: High-precision multi-station formers cold-extrude the internal hex recess and head knurling to precise tolerances, preventing Allen key slipping under high tightening torque.
- Precision Thread Rolling: Rolled metric 6g threads establish precise pitch concentricity and smooth surface finish, significantly reducing anti-galling thread friction during assembly.
- Chemical Pickling & Passivation Bath: Acid washing eliminates iron micro-contaminants introduced by cold-heading tooling, regenerating a pure, dense chromium oxide passive film across all exposed surfaces.
- Optional Anti-Galling Treatment: Specialized dry-wax coatings or electropolishing can be provided upon request to prevent thread galling in high-speed automated assembly.
Industrial Applications of Stainless Steel Socket Head Cap Screw
The compact cylindrical head design allows stainless socket cap screws to sink completely into counterbored holes, making them ideal for space-restricted, hygienic engineering assemblies:
- Food, Beverage & Pharmaceutical Equipment: Assembling sanitary processing machinery, stainless steel pumps, bottling lines, and cleanroom modules.
- Marine Hardware & Offshore Engineering: Securing boat deck fittings, coastal railing brackets, and marine instrumentation panels using SS316 (A4-80).
- Medical Devices & Precision Instrumentation: Laboratory testing equipment, diagnostic machinery, and non-magnetic electronic enclosures.
Quality Control and Export Packaging for Stainless Steel Socket Head Cap Screw
Handan YiHao Fastener enforces comprehensive Quality Assurance (QA) protocols for all export shipments. Inspection procedures include Positive Material Identification (PMI) chemical spectro-analysis to verify Nickel and Chromium content, internal hex key depth gauge testing, and thread ring gauge checks.
All export items are packed in heavy-duty 25kg inner cartons, neatly stacked on ISPM 15 compliant fumigated wooden pallets, and wrapped in protective stretch film to prevent contamination during ocean transit.
Request Factory Direct Pricing for Stainless Steel Socket Head Cap Screws
Looking for a trusted manufacturer in Handan, China for SS304 (A2-70) or SS316 (A4-80) stainless steel socket head cap screws (DIN 912)? Contact Handan YiHao Fastener today for technical datasheets, CAD drawings, sample shipments, and direct bulk export quotes.
