Grade: 50CrVA
Standard No.:
Q/BQB516-2009
Features and application:
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. 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. General, supply specifications for the 1.5 ~ 10.0MM between, multi-annealed state. State for the hot-rolled coil, the use of annealing to reduce the hardness of the ball in order to create conditions for further processing. Chongqing Special Steel Factory 50CrVA are generally annealed plate, eliminating the need for annealing treatment.
Chemical composition:
Carbon C: 0.46 ~ 0.54
Si Si: 0.17 ~ 0.37
Manganese Mn: 0.50 ~ 0.80
Sulfur S: ≤ 0.030
Phosphorus P: ≤ 0.030
Chromium Cr: 0.80 ~ 1.10
Ni-Ni: ≤ 0.35
Copper Cu: ≤ 0.25
Vanadium V: 0.10 ~ 0.20
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
Heat treatment and microstructure specifications:
Standard heat treatment: quenching 850 ℃ ± 20 ℃, oil cooling; tempering 500 ℃ ± 50 ℃ (special needs, ± 30 ℃).
50crva representation
① steel beginning of the two numbers indicate the carbon content of steel, the average carbon content of the very few that, as 40Cr, 25Cr2MoVA alloy steel tube ② main alloying elements, except for a few micro-alloying elements, in general, to a few percent said. When the average alloy content <1.5%, the steel elements generally marked only symbols, but not marked content, but prone to cause confusion in those special circumstances, after the element symbol can also be marked with the number "1", such as steel "12CrMoV" and "12Cr1MoV", the former chromium content of 0.4-0.6%, 0.9-1.2% for the latter, all the remaining ingredients the same. When the average content of alloying elements ≥ 1.5%, ≥ 2.5%, ≥ 3.5% ... ... when, after the element symbol should be marked content, can be expressed as the corresponding 2,3,4 ... etc. For example 18Cr2Ni4WA.
③ vanadium steel V, Ti Ti, Al AL, boron B, and other rare earth RE alloying elements, are micro-alloying elements, although the content is very low, should bid out in steel. For example 20MnVB steel. To 0.07-0.12% vanadium, boron is 0.001-0.005%.
④ High quality steel should be added in the last steel "A", as distinct from the general high quality steel.
⑤ special purpose alloy structural steel, steel, known (or suffix) represents the symbol of the use of steel. For example, rivet screw special 30CrMnSi steel, steel, said to ML30CrMnSi.
