Description Chemical Composition By Size And Steel Grade Size 1.40 mm, steel grade 45#, tensile strength 1650-1850, C 0.42-0.45, Mn 0.5-0.8, Si 0.17-0.37, S ≤0.035, P ≤0.035. Size 2.00 mm, steel grade 70#, tensile strength 1850-2000, C 0.67-0.75, Mn 0.5-0.8, Si 0.17-0.37, S ≤0.035, P ≤0.035. Size 2.20 mm, steel grade 70#, tensile strength 1750-1900, C 0.67-0.75, Mn 0.5-0.8, Si 0.17-0.37, S ≤0.035, P ≤0.035. Size 2.20 mm, steel grade 65#, tensile strength 1700-1900, C 0.61-0.68, Mn 0.5-0.8, Si 0.17-0.37, S ≤0.035, P ≤0.035. Size 4.88 mm, steel grade 80#, tensile strength 1500-1700, C 0.77-0.85, Mn 0.5-0.8, Si 0.17-0.37, S ≤0.035, P ≤0.035.