Grade 2 Hex Bolts are manufactured from low carbon steel, typically 1015-1022. Our Grade 2 bolting meets or exceeds SAE J429 Grade 2. Material is manufactured with rolled threads. Zinc plated material meets or exceeds ASTM F1941. Typical hardness on diameters of 1/4 to 3/4 inch ranges from HRB 80-100 with diameters over 3/4 inch ranging from HRB 70-100. Tensile strength on diameters of 1/4 to 3/4 inch up to 6 inches in length will meet or exceed 74,000 psi. Diameters over 3/4 inch and longer than 6 inches will meet or exceed 60,000 psi.Porteous Fastener Company