Effect of Bainitic Isothermal Treatment on the Microstructure and Mechanical Properties of a CMnSiAl TRIP Steel

TRIP-assisted CMnSiAl steels with a fully martensitic initial microstructure have been studied in order to investigate the effect of partial substitution Si by Al. The steel was fabricated casting sand mold, hot forged, homogenizing, rolling, cold intercritical annealing, and finally, an isothermal bainitic treatment. During annealing at 1023 K (750 °C) for 420 s, matrix consisting 50% proeutectoid ferrite induced after treatment 663 (390 300 ferrite, bainite, retained austenite obtained. This carbon enriched therefore stabilized, Ms lower than original austenite, before Microstructure tensile properties analyzed, comparing these results those corresponding commercial TRIP 780 steel. tests, changes from 8.1 1.9%vol, total elongation 23.2%, which demonstrates effect. Texture analysis showed weak γ-fiber steel, deteriorates drawing maximum during test this obtained 323 (50 °C), correlating present is favored when working within critical zone temperatures Msσ Md. show that Al decreases yield stress, ultimate strength, increases elongation, temperature related 780.