EFFECT OF ROLL FORCE DECREASE IN HOT ROLLINGOF DP600 STEEL GRADE BY USE OF ROLL GAP LUBRICATION

The force required for plastic deformation of steel in the hot rolling process is an important parameter which impacts roll wear, strip steering in finishing stands, shape and profile of the rolled strip and energy consumption. Theoretically, the roll force could be effectively decreased by rolling strips with higher temperatures and a lower speed or by reducing the strips input thickness. Due to the required mechanical properties of hot rolled strips as well as the continuous drive toward increased rolling line productivity and cost optimisation, in most cases, it is impossible to lower roll force by changing these two parameters. Roll gap lubrication effectively decreases the roll force, and lowering the friction between the work roll's surface and rolled material reduces roll force by 5% to 20%. Lower roll force brings obvious results in lower energy consumption, but even more important are benefits coming from lower work roll wear and improved strip shape and profile. These issues are particularly important during the hot rolling of dual-phase steel, which due to relatively low final rolling temperature (FRT), requires a higher roll force resulting from increased steel yield stress at lower temperatures.