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AISI A9
Category Steel
Class Tool steel
Type Air-hardening medium-alloy cold work steel
Designations  United States: ASTM A681 , FED QQ-T-570 , UNS T30109

Composition
ElementWeight %
C  0.45-0.55 
Mn  0.50 
Si  0.95-1.15 
Cr  4.75-5.50 
Ni  1.25-1.75 
Mo  1.30-1.80 
V  0.80-1.40 
Cu  0.25 
P  0.03 
S  0.03 

Mechanical Properties
Properties Conditions 
T (°C)Treatment
Density (×1000 kg/m3) 7.78 25  
Poisson's Ratio 0.27-0.30 25  
Elastic Modulus (GPa) 190-210 25  

Thermal Properties
Properties Conditions 
T (°C)Treatment
Thermal Expansion (10-6/ºC) 12  20-425 more  
Glossary