Class 12.9 black countersunk hexagon screws for knife or knives
Mechanical properties Head markings and mechanical properties Head marking Grade, material & condition Nominal size range [mm] Proof strength [MPa] Yield strength (min) [MPa] Tensile strength (min) [MPa] Core hardness [Rockwell] Class 4.6 Low or medium carbon steel 5–100 225 240 400 B67–95 Class 4.8 Low or medium carbon steel;