65 spring steel 
 Material: 65 spring steel 
 Standard: GB / T 1222-1984 ● Features and Scope: similar performance with 70 spring steel, flexibility and strength slightly, apply to the manufacture of cross-section, less demanding strength, general machine round, square spiral spring machinery such as automobiles, tractors, or train to withstand the vibration of a flat leaf spring and a circular coil spring. ● chemical composition: Carbon C: 0.62 to 0.70 Si Si: 0.17 ~ 0.37 Mn Mn: 0.50 ~ 0.80 SS: ≤ 0.035 phosphorus P: ≤ 0.035 Chromium Cr: ≤ 0.25 Ni - Ni: ≤ 0.25 Copper Cu: ≤ 0.25 ● Mechanical Properties : tensile strength σb (MPa): ≥ 980 yield strength σs (MPa): ≥ the δ10 of 785 elongation (%): ≥ 9 Reduction of area ψ (%): ≥ 35 Hardness: hot-rolled, ≤ 285HB; Cold Drawn ≤ 321HB of the + heat treatment ● Heat Treatment Specification: specification heat treatment: quenching 840 ° C ± 20 ° C, cold oil; tempering 500 ° C ± 50 (special needs, ± 30 ° C). Delivery status: the state of hot-rolled steel to heat treatment or no heat treatment delivery, cold drawn steel to heat treatment delivery.