What is a DIN 7991 countersunk socket screw?

DIN 7991 countersunk socket screws are metric fasteners with a flat countersunk head and internal hex drive designed to sit flush with the material surface.

What angle are DIN 7991 countersunk screws?

DIN 7991 countersunk socket screws typically use a 90 degree head angle to allow the fastener to sit flush with the surface.

What grades are DIN 7991 screws available in?

DIN 7991 screws are commonly manufactured in strength grades 8.8, 10.9 and 12.9 depending on the application requirements.

DIN 7991 Countersunk Socket Screws – Dimensions, Specifications & Applications

12th Mar 2026

What is DIN 7991?

DIN 7991 refers to the German industrial standard for countersunk socket head cap screws. They include DIN 7991 CLASS 12.9, DIN 7991 CLASS 10.9 and DIN 7991 A4

These fasteners feature:

a flat countersunk head
hex socket drive
high-strength alloy steel construction

The countersunk head allows the screw to sit flush with the surface, making it ideal where a smooth finish is required.

DIN 7991 screws are widely used in:

steel fabrication
machinery assemblies
automotive components
construction equipment

DIN 7991 Dimensions Chart

Thread Size	Head Diameter	Head Height	Hex Key
M6	12 mm	3.3 mm	4 mm
M8	16 mm	4.4 mm	5 mm
M10	20 mm	5.5 mm	6 mm
M12	24 mm	6.5 mm	8 mm
M16	30 mm	8 mm	10 mm
M20	36 mm	10 mm	12 mm

Typical Applications

DIN 7991 screws are commonly used where flush fastening is required.

Examples include:

machinery covers
steel fabrication assemblies
structural steel connections
automotive components

Installation Guidance

When installing countersunk socket screws:

ensure the countersink angle matches the screw head
use the correct hex key size
apply appropriate torque settings

Proper installation ensures maximum clamping force and joint reliability.

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