DIN 7991 Flat Head Socket Cap Screws
DIN 7991 Flat Head Socket Cap Screws
ISO Equivalent: ISO 10642 | Countersunk Socket Head Screws
DIN 7991 defines countersunk (flat head) socket cap screws with internal hex drive — designed for flush mounting where the screw head must sit level with or below the surface. Features a 90° countersink angle.
Quick Specifications
Key Features
Flush Mounting
Countersunk head sits flush with the surface — nothing protrudes above the workpiece.
High Torque Hex Socket
Internal hex drive provides superior torque transmission compared to Phillips flat heads.
90° Countersink
Standard 90° included angle matches common countersink tools and sheet metal specifications.
High Strength Options
Available in Class 10.9 alloy steel — significantly stronger than standard machine screws.
Dimension Chart
| Size | Pitch | Head Dia. (dk) | Head Height (k) | Hex Key Size |
|---|---|---|---|---|
| M3 | 0.5 mm | 6.72 mm | 1.7 mm | 2.0 mm |
| M4 | 0.7 mm | 8.96 mm | 2.3 mm | 2.5 mm |
| M5 | 0.8 mm | 11.2 mm | 2.8 mm | 3.0 mm |
| M6 | 1.0 mm | 13.44 mm | 3.3 mm | 4.0 mm |
| M8 | 1.25 mm | 17.92 mm | 4.4 mm | 5.0 mm |
| M10 | 1.5 mm | 22.4 mm | 5.5 mm | 6.0 mm |
| M12 | 1.75 mm | 26.88 mm | 6.5 mm | 8.0 mm |
| M16 | 2.0 mm | 33.6 mm | 7.5 mm | 10.0 mm |
| M20 | 2.5 mm | 40.32 mm | 8.5 mm | 12.0 mm |
Property Classes
Stainless Steel Options
| Grade | Class | Tensile Strength | Best For |
|---|---|---|---|
| A2 (18-8 / 304) | A2-70 | 101,500 PSI | General corrosion resistance, clean appearance |
| A4 (316) | A4-80 | 116,000 PSI | Marine, chemical, medical applications |
Common Applications
DIN 7991 vs ISO 10642
💡 Are They Interchangeable?
Yes — DIN 7991 and ISO 10642 are dimensionally equivalent and fully interchangeable. Both standards specify:
- 90° countersink angle
- Identical head diameters and heights
- Same hex socket sizes
- Compatible thread specifications
Countersink Requirements
For proper seating, machine a countersink to match the head diameter:
Shop DIN 7991 Flat Head Socket Cap Screws
Available in Class 8.8, 10.9, and stainless steel. Sizes M3 through M20.
Shop Flat Head Socket Caps