Effect of finish rolling temperature on microstructure and properties of low carbon steel based on DSCCR production process

Abstract

Based on Donghua steel continuous casting rolling(DSCCR) production line, hot rolling tests rolled at 880, 820 ℃ and 780 ℃ were carried out to study the effect of finish rolling temperature on microstructure and properties of low carbon steel. OM, SEM, EBSD and other characterization methods were used to observe and analyze the microstructure of hot rolled strip at different finish rolling temperatures. Meanwhile, the tensile properties of hot rolled strip were tested and analyzed, and the changes of yield strength, tensile strength and elongation of hot rolled strip at different finish rolling temperatures were compared and analyzed. In addition, the thickness of iron oxide scale of hot rolled strip at different finish rolling temperatures was also measured. The results show that with the decrease of finish rolling temperature, the tensile strength ratio and elongation ratio of the strips decrease from 0.8-0.81 at 880 ℃ to 0.75-0.79 at 780 ℃, the elongation of the strips decrease from 40% at 880 ℃ to 27% at 780 ℃, and n value (strain-hardening exponent)decreases from 0.22 at 880 ℃ to 0.17 at 780 ℃. At the same time, the iron oxide scale of hot rolled strip steel was observed and analyzed. With the decrease of finish rolling temperature, the thickness of the iron oxide scale decreases from 10.2 μm at 880 ℃ to 8.8 μm at 780 ℃, and the decrease of the iron oxide scale sheet can improve the subsequent pickling efficiency and reduce the consumption of pickling.

Keywords

• dsccr
• low carbon steel
• finish rolling temperature
• iron oxide scale
• microstructure