316/A4 Stainless Metric Flat Head Socket Cap Screws

316 Stainless Steel (A4) DIN 7991 Metric Flat Head Socket Cap Screws

When you need a fastener that sits perfectly flush with the surface while delivering high strength and corrosion resistance, DIN 7991 Flat Head Socket Cap Screws are the professional standard. These fasteners feature a flat, countersunk head with an internal Allen or socket hex drive, making them ideal for precision assemblies where clearance and appearance matter.

These fasteners are also commonly referred to as countersunk machine screws, which accurately describes their function. They are fully threaded machine screws designed for use in tapped holes or with nuts in structural and mechanical fastening systems.

Our DIN 7991 flat head socket cap screws are manufactured from A4 grade 316 stainless steel, making them ideal for marine, coastal, and washdown environments where corrosion resistance is critical.

The 90 degree countersunk head allows the screw to sit flush with the mating surface, eliminating snag points and creating a clean finished appearance. This makes these screws especially well suited for:

• Marine deck hardware and fittings
• Boat interiors and cabinetry
• Hinges, latches, and hardware mounting
• Machinery covers and guards
• Aluminum, steel, and composite panels
• Architectural and decorative metalwork

The Allen or socket hex drive allows for high installation torque while maintaining a smooth finished head that resists stripping and wear.

Why DIN 7991 Matters

DIN 7991 defines the countersink angle, head diameter, socket size, and thread geometry so that these flat head socket cap screws fit and perform consistently across all sizes. These are not generic countersunk screws. They are precision metric machine screws designed to properly seat in 90 degree countersinks and deliver predictable clamping force.

Using the correct DIN 7991 screw ensures full surface contact between the screw head and the countersink, which improves load distribution and prevents loosening or material damage.

Material: A4 / 316 Stainless Steel

These screws are made from A4 stainless steel, also known as 316, the preferred alloy for corrosive and saltwater environments.

• Exceptional resistance to rust and pitting
• Highly resistant to saltwater and chlorides
• Strong and durable under load
• Long service life outdoors and in wet environments
• Non-magnetic in most conditions

This is the same stainless used in marine fittings, fasteners, and offshore hardware, and it dramatically outperforms A2, 304, and 18-8 stainless in corrosive environments.