alloy structural steel:40CrNiMoA AISI4340 36CrNiMo4, 1.6510
standard:GB/T 3077-1988
Chemical composition:
C :0.37--0.44
Si:0.17--0.37
Mn:0.50--0.80
S :allow remains content<=0.025
P : allow remains content<=0.025
Cr:0.60--0.90
Ni:1.25--1.65
Cu:allow remains content<=0.025
Mo:0.15--0.25
mechanical properties:
tensile strength b (MPa):>=980(100)
yield strength (MPa):>=835(85)
extensibility   (%):>=12
reduction of area   (%):>=55
ballistic work Akv (J):>=78
notched bar impact strength kv (J/cm2):>=98(10)
rigidity :<=269HB
specimen size:specimen size of rough 25mm
heat treatment regime and metallurgical structure:
heat treatment regime :quenching 850,oil cooling :backfire 600,water cooling ,oil cooling,
deliver position :heat treatment(normalizing,annealing or high-temperature backfire)or no heat treatment,this should be shown on the contract.