20Cr alloy structural steel

Standard: GB / T 3077-1988
● Features and application:
Higher strength and hardenability 15Cr steel, toughness is poor; welding is better, generally without heat treatment after welding. Ministry of strength for the heart to withstand wear and surface higher, a larger size, or shape of the load much more complex and carburizing parts such as gears, gear shaft, cam, piston pin, worm, etc., can be used as working large and medium speed to withstand the impact of load conditioning parts.
● Chemical Composition:
Carbon C: 0.18 ~ 0.24
Si Si: 0.17 ~ 0.37
Manganese Mn: 0.50 ~ 0.80
Sulfur S: to allow the residual content of ≤ 0.035
Phosphorus P: allow the residual content ≤ 0.035
Chromium Cr: 0.70 ~ 1.00
Ni: to allow the residual content of ≤ 0.030
Copper Cu: to allow the residual content ≤ 0.030
● Mechanical Properties:
Tensile strength σb (MPa): ≥ 835 (85)
Yield strength σs (MPa): ≥ 540 (55)
Elongation δ5 (%): ≥ 10
Reduction of area ψ (%): ≥ 40
Impact energy Akv (J): ≥ 47
Impact toughness αkv (J/cm2): ≥ 59 (6)
Hardness: ≤ 179HB
Sample size: Sample size is 15mm rough
● Heat treatment and microstructure specifications:
Standard heat treatment: quenching: the first 880 ℃, the second time 780 ~ 820 ℃, water, oil cooling; tempering 200 ℃, water, air-cooled.
● Delivery status: to heat treatment (normalizing, annealing, or tempering) or heat treatment delivery, delivery status should be indicated in the contract.