OBRABOTKAMETALLOV Vol. 23 No. 3 2021 MATERIAL SCIENCE EQUIPMENT. INSTRUMENTS 6 4 4 Ta b l e 3 Technological constrains, the new rolling mode and results of normal contact stresses calculation Rolling stand No. 7 9 11 Maximum percentage reduction εi.max, % 50 30 25 Maximum rolling force Рi.max, MN 35 28 20 Maximum back tension σi.max, MPa 22 35 47 Maximum front tension σi.max, MPa 31 42 55 Estimated rolling speed υi, m/s 1.97 6.08 11.41 Design strip temperature ti, oС 1,016 975 935 Estimated percentage reduction εi, % 50 20.45 10 Plastic resistance σpl, MPa 174 247 313 Young’s modulus for a strip ЕS, MPa 105,981 110,479 114,922 Rolling force Рi, MN 33.81 14.93 12.4 Maximum estimated normal contact stresses on the plastic section рхmax, MPa 350.1 634.73 837.5 Estimated normal contact stresses in the neutral section рnmax, MPa 341.7 633.85 838 Ta b l e 4 Operating and new rolling schedule and calculation results of maximum normal contact stresses Steel Rolling mode Rolling stand No. εi, % σi-1/σi, MPa рхmax, MPa рхmax, MPa 0.18 C-Cr-Mn-Ti Operating schedule 7 48.5 20/30 337 329.6 9 34.3 30/30 685 682.5 11 21.3 40/40 1,096.5 1,095.7 New schedule 7 50 24/32 393.5 386 9 30 37/43 664 663 11 18.9 49/58 939 938 0.14 C-2 Mn-N-V Operating schedule 7 47.9 20/30 378 370 9 33.8 30/30 750.2 748 11 22.1 40/0 1,245 1,243.4 New schedule 7 50 30/35 441 433 9 30 40/48 732.6 731 11 19.1 50/60 1,023 1,021.9 Conclusions 1. The method of calculation for normal contact stresses in elastic sections of the deformation zone during rolling of low-alloyed structural carbon steels is supplemented by the dependence of the change in the elasticity modulus of the strips on temperature. 2. A regression equation is obtained for predicting the calculated values of the elasticity modulus of such steels as a function of the change in hot rolling temperature.
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