Fixations en acier inoxydable pour environnements difficiles : quand choisir 304 ou 316

If you buy stainless steel fasteners often, you have probably heard the same question many times: “Is 304 enough, or should we pay for 316?”

The honest answer is: it depends on the environment. Strength is usually not the big difference. Corrosion resistance is.

304 vs 316 Stainless Steel Fasteners

The Practical Difference

304 stainless steel is also called A2 in many ISO fastener specifications. 316 stainless steel is commonly called A4. The key upgrade in 316 is molybdenum, which improves resistance to chloride corrosion.

For available grades and product types, review attaches en acier inoxydable.

When 304 Is the Right Choice

Use 304 for Mild Conditions

304 works well where corrosion exposure is moderate. I would normally choose it for:

• Machines d'intérieur
• Armoires électriques
• Food equipment with mild cleaning
• Architectural hardware
• Dry outdoor structures
• Assemblée générale industrielle

It is a solid choice when the fastener is not exposed to salt spray, de-icing salts, seawater, or harsh chemicals.

When 316 Is Worth the Cost

Use 316 for Chloride and Harsh Exposure

316 is the safer option when failure would mean high replacement cost, downtime, or safety risk.

Choose 316 for:

• Coastal construction
• Équipement marin
• Plateformes offshore
• Traitement chimique
• Wastewater treatment
• Seafood and dairy processing
• Outdoor projects exposed to road salt

For a deeper grade comparison, see this guide on Boulons en acier inoxydable 304 vs 316.

Do Not Forget the Full Assembly

Match Bolts, Nuts, and Washers

A 316 bolt with a low-grade or mismatched nut is not a reliable assembly. Keep the material family and strength class consistent.

For sourcing complete assemblies, check boulons et noix ensemble.

Conseil d'achat final

Do not buy “stainless steel” without naming the grade. Write 304/A2 or 316/A4 clearly on the purchase order.

Use 304 when the environment is clean and mild. Use 316 when salt, chemicals, moisture, or maintenance access becomes a real concern. The best stainless steel fastener is not always the most expensive one. It is the one that matches the job site.