51CrV4 Implementation of the standards: EN 10089-2002 Feature 51CrV4 (1.8159) spring steel good mechanical properties and process performance, high hardenability, adding vanadium to steel the grain refinement, reduce heat sensitivity, increased strength and toughness, high fatigue strength, yield ratio is high, but poor welding, cold plastic deformation due to the low. Use 51CrV4 is a relatively high spring, as a large section of the important spring and high-load operating temperature <300 ℃ of the valve spring, piston spring, valve spring. Physical properties Chemical composition 50CrVA (1.8159) spring steel (7) Carbon C: 0.47 ~ 0.55 Si Si: ≤ 0.40 Manganese Mn: 0.70 ~ 1.10 Sulfur S: ≤ 0.030 Phosphorus P: ≤ 0.030 Chromium Cr: 0.90 ~ 1.20 Ni-Ni: ≤ 0.35 Copper Cu: ≤ 0.25 Vanadium V: 0.10 ~ 0.25 Mechanical properties Tensile strength σb (MPa): ≥ 1274 (130) Yield strength σs (MPa): ≥ 1127 (115) Elongation δ5 (%): ≥ 10 Reduction of area ψ (%): ≥ 40 Hardness: hot, ≤ 321HB; cold-drawn + heat treatment, ≤ 321HB Standard heat treatment and microstructure Standard heat treatment: quenching 850 ℃ ± 20 ℃, oil cooling; tempering 500 ℃ ± 50 ℃ (special needs, ± 30 ℃). Delivery status: hot-rolled steel to heat treatment or heat treatment delivery, cold-drawn steel with heat treatment delivery. 60Si2Mn and 51CrV4 both spring steel, mechanical properties are similar. 60Si2Mn mechanical properties: σs ≥ 1176Mpa, σb ≥ 1274Mpa, δs ≥ 5%, ψ ≥ 25% 51CrV4 mechanical properties: σs ≥ 1175Mpa, σb ≥ 1500Mpa, δs ≥ 6%, ψ ≥ 40%, the allowable shear and torsion stress ≥ 1050Mpa. Fatigue life of 300 million times; allowable shear and torsion stress ≥ 1050Mpa. 51CrV4 operating temperature up to 300 degrees Celsius, 60Si2Mn only up to 250 degrees. In addition, 60Si2Mn used for spring, worm spring roll and the following spring manufacturing 30mm diameter, 51CrV4 used for manufacturing large diameter spring.
