Abstract: | After the quenching treatment of the steels, the microstructure contains martensite (hard and brittle) and residual austenite (soft and tenacious). The quantity of residual austenite in the final structure of the quenched steels depends on many factors: the speed of heating, the chemical composition, the speed of cooling, the position of critical points Ms and Mf.
There are several methods to determine the quantity of the residual austenite: the X rays diffraction, the expansion analyze, the metallographic analyze, the magnetic investigations, the ultrasonic investigations.
The quantitative determination of the residual austenite based on the magnetic characteristics, may be realized by measurement of the saturated magnetization, measurement of the coercive field, measurement of the magnetic permeability etc. All these methods have as fundament the correlation between the magnetic properties and the structural constitution of the steels. |
