304 Stainless Steel Hex Socket Countersunk Head Cap Screw M5 M6 M8 M10 | DIN7991 | 55–120mm | 20–100PCS

304 Stainless Steel Hex Socket Countersunk Head Cap Screw — DIN7991 | M5–M10 | 55–120mm

Long-length 304 stainless steel hex socket countersunk (flat head) cap screws to DIN7991 standard, covering M5 through M10 in lengths from 55mm to 120mm. The countersunk head sits flush with or below the surface for a clean, snag-free finish in structural, marine, and outdoor applications where corrosion resistance and flush fastening are both required. The hex socket (Allen key) drive provides high torque transfer without cam-out — essential for the higher clamping forces needed in long-length structural fastening.

Specifications

Thread & Hex Key Reference

Why 304 Stainless Steel for Long Screws?

Long-length screws (55–120mm) are typically used in structural, outdoor, and marine applications where corrosion is a primary concern. 304 stainless steel (A2 grade) provides:

• Excellent corrosion resistance — resists rust in outdoor, coastal, and humid environments
• No surface coating to wear off — unlike zinc-plated carbon steel, the corrosion resistance is inherent to the material
• Food-safe and chemical resistant — suitable for food processing equipment and chemical plant applications
• Long service life — decades of reliable performance in outdoor installations

Key Features

• ✅ DIN7991 standard — consistent dimensional tolerances for reliable fit in countersunk holes
• ✅ 304 A2-70 stainless steel — superior corrosion resistance for outdoor, marine, and structural use
• ✅ Hex socket drive — high torque transfer, no cam-out, works in confined spaces with an Allen key
• ✅ Countersunk head — sits flush with surface for clean, snag-free assemblies
• ✅ Long lengths 55–120mm — covers structural fastening through thick materials
• ✅ M5–M10 range — covers light structural through heavy-duty fastening requirements
• ✅ 20–100PCS packs — from small project to trade supply

Common Applications

• Marine and boat deck hardware fastening
• Outdoor furniture and pergola structural assembly
• Aluminium profile and extrusion structural connections
• Stainless steel fabrication and welding fixtures
• Food processing and catering equipment assembly
• Architectural metalwork and handrail installation
• CNC machine frame and structural fastening
• Solar panel mounting frame assembly

Frequently Asked Questions

Q: Is 304 stainless steel suitable for saltwater / marine environments?
A: 304 SS provides good corrosion resistance in most marine environments. For direct saltwater immersion or highly aggressive coastal environments, 316 stainless steel (A4 grade) is recommended for superior chloride resistance.

Q: Why is 304 SS weakly magnetic?
A: 304 stainless steel is austenitic and non-magnetic in its annealed state. Cold working during thread rolling can induce slight magnetism — this is normal and does not affect corrosion resistance or mechanical properties.

Q: What countersink angle do these screws require?
A: DIN7991 countersunk screws use a 90° countersink angle. Use a 90° countersink bit to prepare the hole for a flush fit.

Package Contents

• 20 / 50 / 100× 304 Stainless Steel DIN7991 Hex Socket Countersunk Screws (size and length as selected)