316 - Stainless steel - Hexagon socket button head screw

Technical Advantages of A4 Button Head Screws

While standard stainless steel works for general use, Grade 316 (A4) is engineered for the extremes. When you combine this marine-grade alloy with the button head design, you get a fastener that is safe (no sharp edges), functional (hex drive), and incredibly durable. This makes it the standard specification for deck fittings on yachts and components in coastal architecture.

Material Composition: A4 vs A2

The performance difference comes down to chemistry. Here is how our A4-70 (316) button head screws compare to the standard A2 (304) version:

Element/Feature	Grade 304 (A2)	Grade 316 (A4)
Molybdenum	None	2.0% - 3.0% (Key for salt resistance)
Nickel Content	8.0% - 10.5%	10.0% - 14.0% (Improves toughness)
Primary Use	General Indoor/Outdoor	Marine, Chemical, Coastal

Quality Assurance

We guarantee the integrity of our marine-grade products. An EN 10204 3.1 Material Certificate verifying the Molybdenum content is available upon request. Please note that third-party inspection services require an additional fee.

Critical Applications

Grade 316 button head screws are essential for:

• Marine Hardware: Securing instrument panels and trim on boats where saltwater exposure is constant.
• Chemical Laboratories: Equipment assembly where accidental spillage of acids might occur.
• Food Processing: Conveyor guards in wash-down areas using aggressive cleaning agents.
• Medical Equipment: MRI machines and surgical robots requiring non-magnetic and sterile fasteners.

Frequently Asked Questions

Should I use anti-seize on 316 stainless screws?

Yes, absolutely. Grade 316 stainless steel is prone to "galling" (cold welding) during installation, especially when tightening a stainless bolt into a stainless nut. Applying a high-quality anti-seize lubricant paste to the threads is critical to ensure smooth installation and future removal.

Can I use these screws on an aluminum boat hull?

You need to be careful. Stainless steel (316) and aluminum are far apart on the galvanic series. In saltwater, the aluminum will corrode rapidly around the stainless screw. To prevent this, you must use a dielectric barrier, such as a nylon washer or a specialized jointing compound (like Tef-Gel) to isolate the screw from the hull.

What is the difference between 316 and 316L?

316L has a lower carbon content ("L" stands for Low Carbon). This makes it better for welding as it prevents carbide precipitation. For standard button head screws that are not being welded, 316 and 316L offer virtually identical corrosion resistance and mechanical strength, and are often used interchangeably in the fastener industry.