M10 M12 1018 Carbon Steel 4.8 5.8 8.8METAL BOLT Carriage Bolt Dacromet 500 h

M10 M12 1018 Carbon Steel 4.8 5.8 8.8METAL BOLT Carriage Bolt Dacromet 500 h

Product Description

Low-carbon blank is zinc-flake coated at 180 °C, achieving 500 h salt-spray with no hydrogen embrittlement risk.

Heat-treatment follows when mechanical properties above 400 MPa are required: medium-carbon grades are quenched and tempered at 550 °C to achieve Grade 8.8 or A307-C strength, while stainless steels are solution-annealed at 1050 °C and water-quenched to restore corrosion resistance. Final finishing is selected for the target environment: zinc electroplating (5–8 µm) or hot-dip galvanizing (45–60 µm) for carbon steel outdoor use, black oxide plus oil for indoor furniture, Dacromet or Geomet for 1000-hour salt-spray demand, and passivation or electropolishing for stainless A2-70/A4-80 bolts used in food equipment.

Key Features

Coating thickness 8 µm equals 40 µm electro-zinc, giving clearance in 9 mm holes without reaming; no white rust keeps apiaries tidy.

The unique square-neck design makes Carriage Bolt the first choice for any joint where access is limited to one side and where a smooth, tamper-resistant head is desired. In timber construction the bolt is dropped into a pre-drilled hole; the square neck pulls into the wood when the nut is tightened on the opposite face, eliminating the need for a wrench on the head side.