Characteristics and scope of application: The strength is slightly higher than that of No. 15 steel, it is rarely quenched, and there is no temper brittleness. Cold deformation plasticity is high, generally for bending, calendering, crimping and hammer arching. The welding performance of arc welding and contact welding is good. The thickness of gas welding is small, and the shape is strict or the shape is complicated. The machinability cold drawn or normalized state is better than the annealed state, and is generally used for manufacturing with low stress and high toughness requirements.

Chemical composition: Carbon C: 0.17 ~ 0.24" silicon Si: 0.17 ~ 0.37 manganese Mn: 0.35 ~ 0.65 sulfur S: ≤ 0.035 phosphorus P: ≤ 0.035 chromium Cr: ≤ 0.25 nickel Ni: ≤ 0.25 copper Cu: ≤ 0.25

Mechanical properties: Tensile strength σb (MPa): ≥ 410 (42) Yield strength σs (MPa): ≥ 245 (25) Elongation δ5 (%): ≥ 25 section shrinkage ψ (%): ≥ 5, hardness : Not heat treated, ≤ 156HB, sample size: sample size 25mm

Heat treatment specification and metallographic organization: Heat treatment specification: normalizing, 910 ° C, air cooling. Metallographic organization: ferrite + pearlite.

Delivery status: Delivery without heat treatment or heat treatment (annealing, normalizing or high temperature tempering). The delivery of the required heat treatment condition shall be indicated in the contract, and the unspecified shall be delivered without heat treatment.