A2 vs A4 Stainless Steel — Which is Best for Marine Hardware?
When choosing marine hardware, one of the most common questions is whether to use A2 stainless steel (304 grade) or A4 stainless steel (316 grade). Both are widely used in boat fittings and fasteners, but they perform differently in marine environments. This guide explains the differences and helps you decide which option is right for your application.
What is A2 Stainless Steel?
- Also known as 304 stainless steel
- General-purpose grade, suitable for most environments
- Corrosion resistance: Good for fresh water, indoor, or non-aggressive environments
- Cost: More affordable than A4
👉 Best for: General boat fittings that aren’t constantly exposed to seawater (e.g., interior fittings, mild outdoor use).
What is A4 Stainless Steel?
- Also known as 316 stainless steel
- Contains molybdenum, which improves corrosion resistance
- Corrosion resistance: Superior protection against saltwater and chlorine
- Cost: More expensive but longer-lasting in marine use
👉 Best for: Hardware exposed to saltwater — cleats, shackles, fasteners on deck, and fittings near the waterline.
Key Differences Between A2 and A4 Stainless Steel
|
Feature |
A2 Stainless Steel (304) |
A4 Stainless Steel (316) |
|---|---|---|
|
Corrosion Resistance |
Good |
Excellent (ideal for saltwater) |
|
Strength |
High |
High |
|
Price |
Lower |
Higher |
|
Best Use |
General fittings |
Marine & harsh environments |
Which Should You Choose for Marine Hardware?
- For saltwater exposure: Choose A4 stainless steel
- For general indoor/outdoor use: A2 stainless steel is usually sufficient
- For critical safety fittings (e.g., shackles, cleats): Always go with A4
Where to Buy Marine-Grade Stainless Steel Hardware
At ADL Components, we stock both A2 and A4 stainless steel marine hardware, including:
👉 Browse our full Marine Hardware Range
Conclusion
When it comes to marine hardware, the choice between A2 and A4 stainless steel depends on the environment. For the UK boating community, A4 (316) is the safer choice for long-term durability against saltwater.