INFLUENCE OF FINISH ROLLING TEMPERATURE ON MICROSTRUCTURE AND PROPERTY OF NON-QUENCHED AND TEMPERED STEEL

摘要

The differences of microstructure and property of non-quenched and tempered bainitic steel under different finish rolling temperatures was analyzed by the methods of color metallographic, scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results show that the sample with finish rolling temperature 870°C, has high yield strength, tensile strength and impact energy. Comparing with finish rolling temperature 750°C and 800°C, the sample has a higher content of bainite phase and bainitic lath is smaller at finish rolling temperature 870°C. Meanwhile, the percentage of retained austenite is 15% and retained austenite has dispersed distribution. It indicates that, when the finish rolling temperature is higher, the experimental steel has fine phase composition, microstructure distribution and excellent mechanical properties.