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Home / Connectors and Fasteners / Grade 12.9 High-Strength Countersunk Hex Socket Screws Flat Head Bolts M3 M4 M5 M6 M8 M10mm

Attributes

Brand -
Category Industrial Small Parts / Connectors and Fasteners
Origin -
Material Alloy Steel
Strength Class Grade 12.9
Thread Size Options M3, M4, M5, M6, M8, M10, M12
Head Type Cylindrical Head
Surface Treatment Black Oxide Coating
Drive Style Hex Socket (Allen)
Compliance Standard DIN 912 / ISO 4762
Thread Coverage Fully Threaded
Hardness Range 39-44 HRC
Country of Origin Imported

5 reviews

A

Anonymous

Mar 31, 2026

Rating: 5/5

Great for automotive use

Used on engine components where high tensile strength is required. Held up well under heat and vibration.

A

Anonymous

Mar 27, 2026

Rating: 4/5

Good but packaging could be better

Bolts are great quality and meet specs, but some were loose in the bag upon arrival. Product itself is fine.

A

Anonymous

Mar 13, 2026

Rating: 5/5

High quality steel

Very strong bolts. Used them on my bike frame assembly. No issues with stretching or breaking.

A

Anonymous

Mar 12, 2026

Rating: 5/5

Exact specifications

Measured them with calipers, they are true to metric specs. Will buy again for future projects.

A

Anonymous

Feb 10, 2026

Rating: 5/5

Perfect for machinery repair

Used these for a CNC machine repair. Fit perfectly and didn't strip under high torque. Very satisfied with the quality.

5 FAQ

Q: What key size do I need for the M6 screws?

A: For M6 Grade 12.9 hex socket cap screws, you typically need a 5mm Allen key.

Q: Can I use these on aluminum parts?

A: Yes, but we recommend using an anti-seize compound to prevent galling between the steel and aluminum.

Q: Are these corrosion resistant for outdoor use?

A: They have a black oxide coating which offers mild corrosion resistance. For harsh outdoor environments, we recommend stainless steel.

Q: Do you sell matching nuts for these bolts?

A: Yes, please search for Grade 12.9 hex nuts in our store to find the matching hardware.

Q: What is the minimum tensile strength?

A: Grade 12.9 fasteners have a minimum tensile strength of 1220 MPa.

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