Austenite is a densely packed lattice structure, resulting in high density, so the volume mass of austenite is smaller than that of ferrite, martensite and other phases in steel. Therefore, when the steel is heated to the austenitic phase zone, the volume shrinks. When the steel is cooled, the volume expands when the austenite is transformed into ferrite - pearlite and other structures, which is easy to cause internal stress and deformation.
Austenite has many dot matrix slip systems, so its plasticity is good, its yield strength is low, and it is easy to process plastic forming. As a result, ingot, billet, and steel are generally heated to over 1100?C and austenized, then forged, plastic machined or machined into parts.
Austenite in common steel is paramagnetic, so austenite steel can be used as non-magnetic steel. However, Fe-Ni soft magnetic alloy with special composition, which also has austenitic structure, has ferromagnetism.
Austenite has poor thermal conductivity and high linear expansion coefficient, which is about twice as high as the average linear expansion coefficient of ferrite and cementite. Therefore, austenitic steel can be used to manufacture thermal expansion sensitive instrument elements. In carbon steel, the thermal conductivity of ferrite, pearlite, martensite, austenite and cementite is 77.1,51.9,29.3,14.6 and 4.2, respectively. It can be seen that, in addition to carburizing, austenitic thermal conductivity is poor, especially the high alloying degree of austenitic steel is poor, so thick steel parts should be cooled and heated slowly in the process of heat treatment, in order to reduce the thermal stress of temperature difference and avoid cracking.