The invention discloses a rolling production method for improving the
toughness of steel on line. A
continuous casting billet is taken as a
raw material. The rolling production method sequentially comprises the following working procedures of billet heating, descaling, rough rolling,
continuous rolling, through-
water cooling, finish rolling through a bar reducing and
sizing mill and cooling through a cooling
bed, and finally a finished product bar is obtained; wherein a rolled material subjected to
continuous rolling is subjected to through-
water cooling to 650-850 DEG C, after through-
water cooling, the rolled material is subjected to self-
tempering to obtain the finish rolling temperature of the bar reducing and
sizing mill, the finish rolling temperature is 500-700 DEG C, and the temperature of the bar on the cooling
bed is 480-650 DEG C. According to the method, KOCKS rolling is adopted for finish rolling of the bar reducing and
sizing mill, proeutectoid ferrite in a non-required form is eliminated by controlling the finish rolling temperature and the
cooling temperature after rolling, the
toughness of the steel is improved, and the grain size,
hardness and mechanical performance of the non-quenched and tempered steel can be controlled by adopting the rapid cooling technology after rolling.