What material is 51CrV4 steel plate?

51CrV4 (1.8159) spring steel has good mechanical and technological properties and high hardenability. The addition of vanadium makes the steel grain refinement, reduces the overheat sensitivity, improves the strength and toughness, has high fatigue strength and yield ratio, but has poor weldability and low cold deformation plasticity.
51CrV4 is a kind of advanced spring, which is used as an important spring with large cross-section and valve spring, piston spring and safety valve spring with working temperature less than 300℃.

Chemical composition of 51CrV4 steel plate
Carbon: 0.47-0.55
Silicon: ≤0.40
Manganese: 0.70-1.10
Sulfur: ≤0.030
Phosphorus: ≤0.030
Chromium: 0.90-1.20
Nickel: ≤0.35
Copper: ≤0.25
Vanadium: 0.10-0.25
mechanical property
Tensile strength σB (MPA): ≥1274 (130)
Yield strength σs (MPA): ≥1127 (115)
Elongation δ5 (%): ≥10
Reduction of area ψ (%): ≥40
Hardness: hot rolling, ≤321HB; cold drawing + heat treatment, ≤321HB.
Heat treatment specification and microstructure of 51CrV4 steel plate.
Heat treatment specification: quenching 850℃± 20℃, oil cooling; tempering 500℃± 50℃ (special needs, ± 30℃).
Delivery status: hot rolled steel shall be delivered in the state of heat treatment or non heat treatment, and cold drawn steel shall be delivered in the state of heat treatment.