🔩 Product Overview: A2 Stainless Steel Hex Head Machine Screws – M3 to M8 (304 Grade)
For applications that require high torque and a secure, easy‑to‑grip head, these A2 stainless steel hex head machine screws are a reliable choice. The external hex head allows you to use a standard wrench or socket for maximum tightening force, making them ideal for machinery, automotive assemblies, and structural fastening. Made from 304 stainless steel, they offer excellent corrosion, oxidation, and heat resistance – suitable for both indoor and outdoor use. Fully threaded with standard coarse metric pitch, available in diameters M3, M4, M5, M6, and M8. Choose your length – perfect for industrial equipment, marine hardware, chemical plants, and general construction.
✨ Why Choose A2 Stainless Steel Hex Head Screws
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A2 stainless steel (304 grade) – Excellent corrosion resistance, oxidation resistance, and heat resistance. High strength and high toughness for demanding environments.
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Hex head design – External hex shape allows use with standard wrenches, sockets, or hex drivers for high torque without stripping.
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Metric sizes M3, M4, M5, M6, M8 – Covers a wide range of applications from small electronics (M3) up to structural fastening (M8).
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Fully threaded, coarse metric pitch – Standard threads: M3x0.5, M4x0.7, M5x0.8, M6x1.0, M8x1.25. Threads run the entire shank length for maximum grip.
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Length measured under the head – Clear measurement standard – hex head not included in length.
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Wide application range – Seawater equipment, chemical industry, dyeing, paper making, marine hardware, industrial machinery, and construction.
📏 Technical Specifications – Hex Head Machine Screws (M3–M8)
| Specification |
M3 |
M4 |
M5 |
M6 |
M8 |
| Thread Diameter (d) |
3mm |
4mm |
5mm |
6mm |
8mm |
| Thread Pitch (p) |
0.5mm |
0.7mm |
0.8mm |
1.0mm |
1.25mm |
| Head Style |
Hex head (external hex, use wrench or socket) |
| Drive Style |
Hex‑key / wrench (not internal hex – external hex requires socket or open wrench) |
| Material |
A2 Stainless Steel (304 / 18-8) |
| Thread Type |
Fully threaded, coarse pitch |
| Length Measurement |
Under head – from flat bearing surface to tip (head not included) |
| Length Options |
Select from options (typical: 6–50mm depending on size) |
❓ FAQs – A2 Stainless Steel Hex Head Screws
🔸 What is the difference between a hex head screw and a socket head cap screw?
A hex head screw has an external hex shape that requires a wrench or socket for installation. A socket head cap screw has an internal hex drive (Allen key) and a cylindrical head. Hex head screws allow higher torque with common wrenches and are easier to use in tight spaces where a socket wrench can access from the side.
🔸 Are these screws fully threaded? How is length measured?
Yes – they are fully threaded from just under the head to the tip. Length is measured from the underside of the head (the flat bearing surface) to the tip, not including the hex head. For example, an M6 x 20mm screw has a 20mm threaded shank.
🔸 Will A2 (304) stainless steel rust in outdoor or coastal environments?
A2 stainless is highly resistant to moisture, rain, and humidity – perfect for most outdoor use. For direct saltwater immersion or heavy coastal spray, A4 (316) stainless is better, but for general outdoor machinery, marine hardware, and chemical equipment, 304 lasts for years without rust.
🔸 What wrench size do I need for M3 through M8 hex head screws?
Typical hex head wrench sizes: M3 uses 5.5mm, M4 uses 7mm, M5 uses 8mm, M6 uses 10mm, M8 uses 13mm (or 5.5, 7, 8, 10, 13mm respectively). A standard metric wrench set will cover these.
🔸 Can I use these screws with nuts, or are they for tapped holes only?
These are standard machine screws – they work with matching metric nuts (M3–M8) or in pre‑tapped holes. For best corrosion resistance, pair them with A2 stainless nuts.
🔸 What lengths are available for each diameter?
We offer a range of lengths – typical: M3: 6–30mm, M4: 8–40mm, M5: 10–50mm, M6: 12–60mm, M8: 16–80mm. Please select your desired length from the dropdown options. If you need a length not listed, contact us.
