Variation of microstructure and mechanical properties of medium Mn steels with multiphase microstructure

Specimens of medium manganese steels with different manganese contents were austenised at 850°C for 30 min followed by intercritical annealing and water quenching at three different temperatures with different times. After heat treatments, mechanical properties were measured through tensile test. X-ray diffraction, electron back scattered diffraction and scanning electron microscopy examinations were also performed. Results indicate that annealing time, annealing temperature and manganese content all affect the final microstructure, which may consist of ferrite, retained austenite and fresh lath martensite, and variation of microstructure leads to different mechanical properties of steel.