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Understanding stainless steel fasteners isn’t just about knowing what “A2” or “A4” means; it’s about decoding a global language of material science, standardization, and mechanical performance.
In previous blogs, we explored the basic differences between A2 and A4 stainless steel. Now, in this expanded blog, we’re tackling how stainless fasteners are named, why different regions use different codes, and how to navigate the international stainless steel standardization alphabet soup.
What Does “Nomenclature” Even Mean?
In scientific terms, nomenclature is a system for naming things. In the world of fasteners, it’s how we classify stainless steel, whether you’re ordering in the U.S., Germany, or Japan. It’s also what helps you understand how 18-8 stainless steel, A2-70, or A4-80 all relate to each other (yes, they do!).
This system matters, especially when sourcing metric fasteners globally or comparing certifications across ASTM, ISO, DIN, ANSI, JIS, and other standards.
Say My Name: The Cross-Cultural Identity of Stainless Steel
Let’s start with some metric fastener humor:
18-8 stainless steel walks into class. The teacher calls roll:
“18-8?”
It raises its hand: “It’s pronounced A2.”
So… what is 18-8?
18-8 is shorthand for 18% chromium and 8% nickel, a widely used austenitic stainless steel composition. But here’s where it gets tricky:
- In Europe, that same material is typically labeled A2 (austenitic, grade 2).
- In the U.S., it may still be labeled 18-8 or match to ASTM 304.
- In Japan, it might be listed under a JIS designation.
- On your RFQ, it might show up as A2-70, A2-12H, or even something like 1.4301 (the EN standard number).
That’s where Eurolink’s expertise comes in, we help buyers, engineers, and sourcing teams translate this alphabet soup into the metric fasteners they actually need.
Breaking Down the Naming System
Let’s demystify what’s really in a stainless fastener name like A2-70.
Step 1: The Letter – Metallurgical Class
- A = Austenitic (non-magnetic, corrosion-resistant)
- C = Martensitic (hardenable, magnetic, less corrosion resistance)
- F = Ferritic (some corrosion resistance, magnetic)
Eurolink specializes in A-series fasteners, primarily A2 and A4, because of their superior corrosion resistance and compatibility with a wide range of industrial and outdoor applications.
Step 2: The Grade – Chemical Composition
- A1 to A5 classify different austenitic stainless steel families
- A2 = General-purpose, 18/8 stainless (comparable to 304)
- A4 = Marine-grade stainless with added molybdenum (comparable to 316)
- A2 = 18% Cr / 8% Ni
- A4 = 16% Cr / 10% Ni / 2–3% Mo
Step 3: The Property Class – Mechanical Strength
The final number (e.g., -50, -70, -80) denotes tensile strength and yield strength.
|
Property Class |
Tensile Strength (MPa) |
Typical Use Case |
|
A2-50 |
500 MPa |
Light-duty, general use |
|
A2-70 |
700 MPa |
Most common for industrial use |
|
A4-80 |
800 MPa |
High-strength + high corrosion environments |
Did You Know? A4-80 stainless steel is one of Eurolink’s most in-demand fasteners for marine, food-grade, and chemical processing environments. We stock one of the largest inventories of A4-80 in North America.
What About A2-12H, A2-30H, and the DIN Stuff?
If you’re sourcing from Germany or working with DIN specs, you may see terms like A2-12H or A2-25H.
These refer to specific property classes defined under DIN standards and are often used for special parts like set screws, dowels, or studs, not your everyday hex bolts.
Here’s how it works:
- A2-12H: Typically a set screw, lower mechanical strength
- A2-70: Hex bolt, machine screw, or similar general-purpose item
- A4-80: Higher tensile strength, often used in critical corrosion-prone applications
At Eurolink, we help you match the application with the correct grade and class, so you don’t have to memorize DIN specs or cross-reference ISO charts yourself.
Why Austenitic Stainless Is the Go-To for Metric Fasteners
Most fasteners labeled A2 or A4 fall under the austenitic stainless steel family.
This means they are:
- Non-magnetic
- Corrosion resistant throughout (not just surface-coated)
- Excellent in high-humidity or chemically aggressive environments
- Ideal for food equipment, marine use, medical devices, and clean manufacturing
Other types, like martensitic or ferritic steels, may have advantages in niche applications (e.g., high hardness or resistance to chloride), but they are magnetic and less commonly used for fasteners in global manufacturing.
Frequently Asked Questions (FAQ)
Q: What’s the difference between A2 and A4 stainless?
A2 is general-purpose 18-8 stainless (comparable to 304). A4 contains molybdenum for extra corrosion resistance (comparable to 316) and is ideal for marine and chemical exposure.
Q: Is A4-80 stronger than A2-70?
Yes. A4-80 fasteners have a higher tensile strength and are better suited for high-load environments where corrosion resistance is also critical.
Q: Are A2 and 18-8 the same?
They’re often used interchangeably, but regional standards may vary slightly. Both describe an austenitic stainless with similar chemical makeup.
Q: Can I replace A2-70 with A4-70?
Yes. A4-70 has similar strength but better corrosion resistance. However, never downgrade strength classes without engineering approval.
Q: Does Eurolink stock A4-80 stainless fasteners?
Yes, we stock one of the largest selections of A4-80 stainless in North America, including bolts, screws, and specialty items.
Sourcing Stainless Shouldn’t Be Confusing
Stainless steel fasteners are used in high-performance environments where strength and corrosion resistance are non-negotiable. But interpreting all the codes, names, and numbers can feel like learning a new language.
That’s where Eurolink Fastener Supply Service comes in.
We specialize in metric fasteners, including stainless grades like A2-70 and A4-80, hard-to-find DIN specs, and custom sourcing from trusted European manufacturers. Whether you're planning months ahead or facing a critical production delay, our FAST, FASTER, and FASTEST freight options give you flexible delivery solutions:
- FAST: Each month, we ship out one consolidated sea freight shipment from Europe that arrives at our U.S. facility within 7-8 weeks of shipping. This is our most affordable FAST shipping option from Europe.
- FASTER: Each Wednesday, we ship out one consolidated air freight shipment from Europe that arrives at our U.S. facility within 1-2 weeks of shipping. This speeds up delivery when you need it FASTER.
- FASTEST: On request, we also offer an Express air freight option that normally ships from Europe within 24-48 hours after an order is placed and arrives at our U.S. facility within 3-5 business days. This is our FASTEST option from Europe.
No matter your timeline, Eurolink helps you source metric fasteners with speed and confidence.
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