The effect of isothermal holding on the microstructures and mechanical properties of a low carbon alloy steel

► A mixed microstructures of martensite and lower bainite were obtained. ► The 3D morphology of lower bainite was lath-, plate-, rod-like and lenticular. ► The prior formation of lower bainite was responsible for the higher strength. ► The optimized mechanical properties can be realized by controlling holding time.