The Ultimate Guide to Important Metric Fastener Grades and Materials

[Eurolink] The Ultimate Guide to Important Metric Fastener Grades and Materials

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When it comes to sourcing metric fasteners, knowing your grades and materials isn't just helpful, it's essential. But not all grades are created equal, and not all of them are as commonly used. At Eurolink Fastener Supply Service, we know what actually matters in the field because we’ve been helping customers navigate this landscape for over 25 years.

This guide highlights the metric fastener grades and materials that actually see use, based on decades of experience and insight from our expert sales team. If you're here for brass, plastic, or a deep dive into 3.6 bolts, you won’t find much, because those aren't what our customers are really using.

The Only Alloy Steel Grades You Really Need to Know

8.8: The Starting Point

This medium carbon steel fastener is quenched and tempered and is the most commonly used metric bolt in the world. It offers an ideal balance of strength, ductility, and affordability.

Tensile Strength: ~800 MPa
Typical Applications: Machinery, construction, automotive, and general use
Key Benefits: Widely available, economical, and reliable for everyday applications

10.9: Built for Load

When the project calls for a stronger fastener, 10.9 delivers. These bolts are made from quenched and tempered alloy steel and can handle higher mechanical stress than 8.8.

Tensile Strength: ~1,040 MPa
Typical Applications: High-stress machinery, automotive suspension, structural joints
Key Benefits: Ideal for dynamic loads, better fatigue resistance, dependable under pressure

12.9: The Heavyweight

When you're not messing around, 12.9-grade bolts are the strongest commonly used alloy steel fasteners. Made from high-grade alloy steel, they offer superior mechanical strength.

Tensile Strength: ~1,220 MPa
Typical Applications: Heavy equipment, high-torque settings, and precision installations
Key Benefits: Maximum strength-to-size ratio, perfect for space-limited high-load designs

Grades Not Worth the Ink

Grades like 3.6, 4.6, 4.8, and 5.8 might show up in standards, but we don't carry them, and our customers don’t ask for them. Same with 14.9, it exists, but we’ve never sold one in our 25 years of being in business.

The Stainless Steel Grades That Matter

A2 (304): The Industry Workhorse

Austenitic stainless steel that offers good corrosion resistance for most environments.

Strength: Medium
Corrosion Resistance: Good
Typical Applications: Indoor, mildly corrosive environments, architectural hardware
Key Benefits: Cost-effective corrosion resistance, easy to machine and weld

A4 / A470 (316): Marine-Grade Muscle

This molybdenum-enhanced stainless steel provides excellent corrosion resistance in harsher environments.

Strength: Comparable to A2
Corrosion Resistance: Excellent
Typical Applications: Marine, chemical, and food processing industries
Key Benefits: Better performance in saltwater and acidic conditions

A480: Our Stainless Steel of Choice

Offering a higher strength profile and outstanding corrosion resistance, A480 is the top-tier choice for demanding environments.

Strength: High
Corrosion Resistance: Superior
Typical Applications: High-performance, demanding environments, chemical processing, outdoor installations
Key Benefits: Combines corrosion resistance with improved mechanical strength; stocked and supported by Eurolink

Other Materials: Niche but Necessary

Brass

Non-sparking, decorative, and corrosion-resistant. Brass fasteners are favored in environments where conductivity or aesthetics matter.

Used In: Plumbing, electrical, low-friction applications, antique restoration
Key Benefits: Conductive, non-magnetic, visually appealing, easy to machine

Aluminum

Lightweight and corrosion-resistant. Though not as strong as steel, aluminum is ideal when weight savings are critical.

Used In: Aerospace, lightweight construction, electronics
Key Benefits: Lightweight, corrosion-resistant, recyclable, non-sparking

Plastic

Non-conductive and lightweight. Plastic fasteners are ideal for electrical insulation or applications where metal isn't suitable.

Used In: Electronics, insulation, low-load applications, chemical exposure environments
Key Benefits: Rust-proof, non-magnetic, excellent for specialty industrial applications

These materials may not be as common as steel, but when the application calls for them, you need to know your options.

Popular Eurolink Products to Know

A4-80 Stainless Steel Fasteners

Since 2013, our A4-80 Stainless Steel line has set the standard for strength and corrosion resistance. Ideal for marine environments, outdoor structures, and food-grade facilities, this line is stocked extensively and tested rigorously to meet industry standards. Eurolink is the largest stockholder of A4-80 in North America.

Hot Dip Galvanized 8.8 Hex Head Cap Screws

Our unique tapped-undersized (tZn) hex head cap screws are engineered for thick plating applications without compromising thread compatibility. Available in both DIN and ISO standards, from M6 to M20, they’re perfect for high-stress, corrosion-sensitive applications. Eurolink is proud to be the only stocking distributor of this line in North America.

Metric Structural Bolts – Galvanized and Plain Finish

Made from Class 10.9 steel and manufactured to DIN EN 14399-4, our structural bolts are designed for maximum strength and corrosion protection. With sizes from M12 to M30 and full HV sets (including nuts and washers), these are trusted by engineers for use in bridges, industrial builds, and critical structures.

Metric Torx Screws

Our line of metric Torx screws is crafted for high torque transfer and tamper resistance. These star-drive fasteners reduce cam-out and provide better engagement than traditional Phillips or slotted heads.

Applications: Electronics, automotive, industrial equipment
Key Benefits: Increased torque capacity, precision installation, reduced driver wear

Experience the Eurolink Advantage

Whether you're sourcing 8.8 bolts for an automotive application or A480 stainless for something a little more high-tech, our expert sales team is here to help. We don’t just source and sell hard-to-find metric fasteners; we help you find the right product for your specific needs, and make sure you get treated with the kind of customer service you actually want to remember.

Need it yesterday? We offer Fast, Faster, and Fastest freight options, so you can get the parts you need on your timeline.

Let’s Get to Work

At Eurolink, we make sourcing metric fasteners simple, reliable, and personalized. Ready to find the right grade and material for your next project? Contact our team today and let us help you make the right connection. And don’t forget to download our line cards to see our full product range.