Microstructure and Mechanical Properties of Hot Rolled Low Silicon TRIP Steel Containing Phosphorus and Vanadium

The microstructure characteristics and mechanical properties of a low-silicon TRIP steel containing phosphorus and vanadium at different finish rolling temperatures were studied by laboratory hot rolling experiments. Different ratios of multiphase microstructure (ferrite, granular bainite and retained austenite) are obtained. With a decrease in finish rolling temperature, the volume fractions of ferrite and retained austenite increase. EBSD analysis reveals that most of the ferrite grains are fine, and decreasing of finish rolling temperature leads to an increase in low angle boundaries. Under the joint effects of fine grain strengthening, dislocation strengthening and precipitation strengthening, higher strength is obtained. When the finish rolling temperature is decreased to 800 °C, the steel has excellent mechanical properties: Rp0.2 = 470 MPa; Rm = 960 MPa; Rp0.2/Rm = 0.49; A50 = 19.7%; n = 0.25.