Introduction to austenite grain
Austenite is an interstitial solid solution of carbon in γ-Fe and has a face-centered cubic structure. Due to the limitation of the volume factor (the radius of carbon atoms is 0.077nm, and the maximum gap of the γ-Fe crystal structure, that is, the octahedral gap radius is 0.053nm), the maximum solid solubility of carbon in γ-Fe is only 2.11% (mass fraction) .