hardness will range from HRC 31-39

On diameters over 2 1/2 inches

5/8-18 x 6 Grade 8 Hex Cap Screw Yellow Zinc Plated

5/8-11 x 7 Grade 8 Hex Cap Screw Yellow Zinc Plated

9/16-12 x 5 Grade 8 Hex Cap Screw Yellow Zinc Plated

7/8-9 x 1 3/4 Grade 8 Hex Cap Screw Yellow Zinc Plated 5/8-11 Grade 5 Hex Cap Screws Zinc Plated hardness will range from HRC7 8 9 x 1 3 4 Grade 8 Hex Cap Screw Yellow Zinc Plated . Grade 8 Hex Cap Screws are manufactured from medium carbon alloy steel. In diameters 1 4 to 1 1 2 inches our Grade 8 material meets or exceeds SAE J429 Grade 8 specifications. Diameters over 1 1 2 inches meet or exceed ASTM A354 Grade BD. All material is manufactured with rolled threads. Yellow zinc plated bolting will meet or exceed ASTM F1941. Typical hardness on diameters 1 4 to 2 1 2 inches