Issue 37

U. Muhin et alii, Frattura ed Integrità Strutturale, 37 (2016) 312-317; DOI: 10.3221/IGF-ESIS.37.41 316 Figure 2: Calculated parameters of hot rolling and accelerated cooling. Strip 3x1250 mm of steel 08U (tr = 1000 °C , Vth = 9 m/s, a = 0,026 m/s, tf = constant (840 °C ), cooling temperature (tc) + 640 °C , QMKO = 0; tr = 1000 °C , Vth = 11,2 m/s, a = 0, tf = constant, QMKO = constant, tc = 640 °C ; in Fig. 2A, - water slow in Fig. 2B, m 3 /h; Fig. 2C – average grain size after finishing group, mcm, in Fig. 2C and number of cooling units in Fig. 2D). Rolling without acceleration in the finishing train almost completely stabilize the cooling conditions of the band on the run-mill roller table. Temperature increase by the end of the rolling length of the bar and the stabilization conditions of accelerated cooling can solve the problem of a uniform microstructure of metal for a significant proportion of the bands mix mill 2000. Application betweenstand cooling of size bands and temperature regimes rolling limited to a maximum filling rate band, which for the mill 2000 is 12.5 m/s. This level is the maximum speed of a gas due to the necessity of accident-free transportation of the front end of the strip to a discharge roller conveyor mill due to the aerodynamic effect Stabilization of metal structure along the strips which use rolling of between stand cooling impossible can be achieved with high values of acceleration of finishing group. The task of rolling mode destination, depending on the thickness of the strip and the required temperature level to the end of the rolling mill 2000 mix resolved on the basis of the developed mathematical model of the thermal state of the metal. Calculation results are presented in Fig. 3. Figure 3: Assignment mode rolling strips in finishing group: a) tr = 1000°C; b) tr = 1030°C. (A - unreachable area, B - rolling with hither acceleration, C - rolling with QMKO = var).