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Standard stainless fasteners hold up well indoors, but the moment a project moves outdoors — onto a boat, a dock, a coastal fence, or a food-processing fixture — the difference between 304 and 316 stainless steel becomes very real. Fabricators, marine builders, equipment manufacturers, and outdoor construction professionals who need a socket cap head screw that won’t rust, pit, or seize in salt air or wet conditions need 316 stainless steel socket cap screws in the exact diameter and length for the job.
Each pack contains 316 stainless steel (A4 grade) socket cap head machine screws in your selected size and quantity (1, 2, 5, or 10 pieces). Thread diameters range from M2 (approx. 5/64”) to M12 (approx. 15/32”), with lengths from 4mm (approx. 5/32”) to 150mm (approx. 5-29/32”), covering a wide range of panel thicknesses and engagement depths. The socket cap head profile features a tall cylindrical head with a hex socket (Allen) drive, allowing high torque application with a standard hex key or bit driver. The 316 alloy adds molybdenum to the chromium-nickel base, providing significantly better chloride and salt-spray resistance than standard 304 (A2) stainless.
These 316 stainless socket cap screws are well suited for marine hardware installation on boats, docks, and coastal structures, outdoor furniture and architectural metalwork in coastal or humid climates, food-processing and chemical-handling equipment where corrosion resistance and cleanability matter, and general machinery assembly where a high-torque hex drive fastener with long-term corrosion resistance is required.
| Drive Type | Hex Socket (Allen / Hex Key) |
|---|---|
| Head Style | Socket Cap Head (tall cylindrical) |
| Material | 316 Stainless Steel (A4 grade) |
| Finish | Natural stainless (uncoated) |
| Property Class | Typically A4-70 (approx. 700 MPa tensile strength) |
| Thread Standard | ISO Metric Coarse (M2 through M12) |
| Available Diameters | M2, M2.5, M3, M4, M5, M6, M8, M10, M12 |
| Available Lengths | 4mm (5/32”) to 150mm (5-29/32”) — see variant options |
| Pack Quantities | 1 Pcs / 2 Pcs / 5 Pcs / 10 Pcs |
| Magnetic Properties | Generally low magnetic permeability (non-magnetic in annealed state) |
| Corrosion Resistance | Excellent — suitable for marine, coastal, and chemical environments |
| Recommended Hex Key | 1.5mm (M2) to 10mm (M12) — see variant for exact size |
| Country of Origin | Contact us to confirm |
A general rule is to select a length that provides at least 1.5× the screw diameter of thread engagement in the base material. For example, an M6 screw fastening a 10mm panel into aluminum would typically need at least 9mm of thread engagement, so a total length of around 20–25mm is generally appropriate. Available lengths range from 4mm (approx. 5/32”) to 150mm (approx. 5-29/32”). Measure your panel thickness and add the required engagement depth before selecting your size.
316 stainless steel (also called A4 stainless) contains molybdenum in addition to chromium and nickel, which significantly improves its resistance to chloride corrosion compared to 304 (A2) stainless. This makes 316 the preferred choice for marine environments, coastal installations, chemical processing, and any application with prolonged exposure to salt water or chloride-containing solutions. For standard indoor or mild outdoor use, 304 is generally sufficient, but 316 provides a meaningful upgrade in corrosion resistance for demanding environments.
Yes. 316 stainless steel is widely used in marine hardware, boat fittings, dock hardware, and coastal construction precisely because of its superior resistance to salt spray and chloride corrosion. While no stainless steel is completely immune to corrosion in all conditions, 316 grade is generally considered the standard choice for marine-grade fasteners in most recreational and light commercial marine applications.
These are ISO metric machine screws (M2 through M12) with standard coarse metric threads. They are compatible with standard metric nuts, threaded inserts, and tapped holes machined to ISO tolerances. They are not compatible with UNC/UNF inch-standard threads.
The required hex key size depends on the screw diameter. As a general reference for socket cap head screws: M2 typically uses a 1.5mm hex key, M2.5 uses 2mm, M3 uses 2.5mm, M4 uses 3mm, M5 uses 4mm, M6 uses 5mm, M8 uses 6mm, M10 uses 8mm, and M12 uses 10mm. Always verify with the specific fastener before installation.
316 stainless steel socket cap screws are generally rated at property class A4-70 (approximately 700 MPa tensile strength). They are suitable for most general-purpose and marine fastening applications but are not as strong as high-tensile steel grades such as 8.8 or 10.9. For structural or high-load applications, consult an engineer to confirm the appropriate fastener grade before ordering.
A socket cap head screw has a tall, cylindrical head with a hex socket drive. The taller head provides a larger bearing surface and allows higher torque application compared to a button head, making it a better choice for applications where clamping force is important. It is commonly used in machinery, equipment assembly, and structural fastening where a recessed or flush-mounted fastener is needed and high torque is required. Button heads are generally preferred when a lower profile is needed in visible or clearance-sensitive locations.
