Effect of Tempering Temperature on Microstructure and Mechanical Properties of As-rolled Low Carbon Baintic Steel

A low carbon bainitic steel was hot rolled and tempered,the influence of tempering temperatures on the microstructure and mechanical properties of the steel was studied by using multi-function material testing machine and optical microscopy.The results indicate that the microstructure of the low carbon bainitic steel consisted of lath-shaped bainite,granular bainite and quasi-polygonal ferrite,and the proportion of each kind of microstructure changed with the tempering temperatures.Tempering temperatures had distinct effect on yield strength of the tested steel,and less effect on the ultimate tensile strength.The yield ratio increased with the increase of tempering temperature.