The composition of austenite
Austenite generally consists of equiaxed polygonal grains with twins in them. At the end of the heating transition, the austenite grains are relatively small and the grain boundaries are irregularly curved. After a period of heating or holding, the grain will grow and the grain boundary will tend to flatten. In the iron-carbon phase diagram, austenite is a high temperature phase, which exists above the critical point A1 temperature and is formed by the reverse eutectic transition of pearlite. Austenite can be stabilized at room temperature when enough chemical elements, such as Ni and Mn, are added to the steel, such as austenite steel.
The ferrite phase changes into austenite at 912°C to 1394°C, and the body centered cubic structure becomes face-centered cubic. The strength of austenite is low, but its capacity to dissolve carbon is high (2.04% carbon at 1146°C). Austenitic stainless steel is commonly used in the food industry and surgical equipment.