Two kinds TRIP steel with reduced Si content (0.6%Si), which differ in their Mn content (1.3%Mn and 1.8%Mn respectively), are inves-igated. The steel sheets are intercritically annealed, and followed by the isothermal holding in the bainitic transformation zone. Micro-structure analysis and tensile tests are reported. The volume fraction of retained austenite in the microstructure is measured by means of X-ray diffraction. The TRIP steel with low Mn content has a lower retained austenite fraction and inferior mechanical properties. Studies show that the increment of Mn content leads to a larger content of retained austenite and an improvement of both tensile strength and elongation. The partition of Mn and Si during the intercritical annealing is reported. Mn does not exhibit any tendency to redistribute during typical intercritical annealing periods.
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