Description
Reviews
| Brand | - |
| Category | Industrial Small Parts / Connectors and Fasteners |
| Origin | - |
| Material | Alloy Steel |
| Strength Grade | 12.9 |
| Surface Finish | Black Oxide |
| Head Type | Socket Cap Head |
| Drive Type | Hex Socket (Inner Hex) |
| Thread Standard | Metric Coarse |
| Available Sizes | M3, M4, M5, M6, M8 |
| Hardness | HRC 39-44 |
| Special Feature | Knurled Under Head |
| Manufacturing Standard | DIN 912 / ISO 4762 |
Anonymous
Apr 24, 2026
Rating: 5/5
Excellent strength for machinery
Used these 12.9 grade screws for a custom engine mount. The hardness is genuine and they did not strip under high torque. The black oxide finish looks professional too.
Anonymous
Mar 24, 2026
Rating: 4/5
Good value bulk pack
Great quality for the price. Only giving 4 stars because the hex key needed was not included, but the bolts themselves are top notch hardened steel.
Anonymous
Mar 14, 2026
Rating: 5/5
Perfect fit for M5 projects
Ordered the M5 size for my 3D printer frame. The threads are clean and the knurled head helps prevent loosening due to vibration. Highly recommended.
Anonymous
Feb 16, 2026
Rating: 5/5
Exactly as described
Needed extended length bolts for a thick assembly. These reinforced bolts handled the load without bending. Fast shipping and well packaged.
Anonymous
Feb 14, 2026
Rating: 5/5
High quality finish
The black oxide coating is even and provides decent corrosion resistance for indoor use. The cup head sits flush as expected. Will buy again.
Q: Are these screws rust-proof for outdoor use?
A: The black oxide finish provides mild corrosion resistance. For harsh outdoor environments, we recommend applying additional grease or using stainless steel alternatives.
Q: Do you offer bulk discounts for over 1000 units?
A: Yes, we offer tiered pricing for bulk orders. Please contact our sales team directly through the store page for a custom quote.
Q: What is the recommended torque for the M6 size?
A: For Grade 12.9 M6 bolts, the typical torque specification is around 10-12 Nm, but please consult a torque chart for your specific application and lubrication conditions.
Q: Can these be used with aluminum parts?
A: Yes, but be cautious of galvanic corrosion between steel and aluminum. Using an anti-seize compound is advised to prevent seizing and corrosion.
Q: Is the thread length full or partial?
A: These are fully threaded bolts across all available sizes (M3 to M8), ensuring maximum grip length for your assembly.
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