Effects of Final Rolling Temperature on Microstructure and Mechanical Properties of Ti-Microalloyed Q345B Steel

Q345B Ti-microalloyed steel containing 0.8wt% Mn and 0.05wt% Ti were designed on the base of Q345B steel, and then the steel was final-rolled at 820, 850,880 ℃, and the effects of final-rolling temperature on microstructure and mechanical properties were studied. The results show that yield strength and elongation of the tested steel increased first and then decreased with the increase of final rolling temperature, when the final temperature was 850 ℃, yield strength and elongation up to the maximum, and they were 490 MPa and 34.0%, respectively. However, tensile strength gradually decreased with the increase of final rolling temperature, this due to the growing ferrite grains. The optimal mechanical properties were obtained for the tested steel at final rolling temperature of 850 ℃.