Class 10.9 black countersunk head hexagon socket head screws M2/M3/M4/M5 flat head screws and bolts M6/M8/M10/M12

Main Advantages

1. Superior Mechanical Strength
   
   
   Class 10.9 is a high-strength bolt grade treated by quenching and tempering heat treatment. Its tensile strength ≥ 1040MPa and yield strength ≥ 940MPa. It features outstanding load capacity, excellent resistance to tension, fracture and fatigue. It can withstand heavy loads and frequent vibration without slipping or breaking easily.
2. Concealed Countersunk Design
   
   
   With a 90° tapered countersunk head, the screw head sinks completely into the countersunk hole after tightening, resulting in a smooth, flush surface without protrusions. It avoids scratches to personnel, cables and matching components, delivering a neat overall appearance.
3. Stable Hexagon Socket Drive
   
   
   The internal hexagon drive provides a large force-bearing area for the Allen wrench, preventing slippage and enabling uniform, controllable high tightening torque. Compared with cross recess screws, it rarely suffers from slot cracking or thread stripping, boasting superior durability for repeated assembly and disassembly.
4. Excellent Locking & Anti-loosening Performance
   
   
   Benefiting from high-strength material and high-torque fastening capability, it maintains stable clamping force under equipment vibration and temperature fluctuation, far less prone to loosening over time than ordinary 4.8/8.8 grade screws.