Analysis on Thermal History of Slab through BP-HR Process

The temperature evolution through breakdowning,reheating,stack cooling and water descaling for bloom with dimension of 325×280 mm² had been studied by means of numerical simulation in this paper. The calculations show that the temperature at corner of transferred bar after 9-passes breakdowning to 160×160 mm² billet is 990 ℃,while it decreases down to 1 012 ℃ for middle section of billet surface.50 minutes reheating can bring the cold charged billet to the temperature of 1 000 ℃,while 40 min utes is sufficient to reheat the hot charged billet up to 1 060 ℃ required for rolling. For the slab after stack cooling for 48 hs,center temperature of slab on the top of stackcooled down to about 20 ℃,while for the slab at middle of stackthat temperature was about 80 ℃. Cooling rate of slab locating from the top to down of stack gradually slows down varing from 8.3 to 15.3 ℃/h and average value is 10.44 ℃/h. Regarding hot rolled billet after descaling section,corner temperature was about 1 053 ℃,and edge center temperature approximates 1 055 ℃. Temperature change through descaling is about 15 ℃.