alloy structural steel:20CrNiMo ASTM8620 1.6523 20NiCrMo2
standard:GB/T 3077-1999
Chemical composition:
C :0.17~0.23
Si:0.17~0.37
Mn:0.60~0.95
S :allow remains content≤0.035
P :allow remains content≤0.035
Cr:0.40~0.70
Ni:0.35~0.75
Cu:allow remains content≤0.030
Mo:0.20~0.30
mechanical properties:
tensile strength σb (MPa):≥980(100)
yield strength σs (MPa):≥785(80)
extensibility δ5 (%):≥9
reduction of area ψ (%):≥40
ballistic work Akv (J):≥47
notched bar impact strength αkv (J/cm2):≥59(6)
rigidity :≤197HB
specimen size:specimen size of rough 15mm
●heat treatment regime and metallurgical structure:
heat treatment regime :quenching 850℃,oil cooling ;backfire200℃,air cooling .
●deliver position :heat treatment(normalizing\annealing or high-temperature backfire)or no heat treatment,this should be shown on the contract.