Temperature Field and Mechanical Properties for Products of Square Billet on Direct Rolling

The continuous casting square billets are directly transferred into rolling stands immediately after being cut off.An uneven temperature field occurs on the billet as a result of elimination of reheating step.The temperature field of billets being directly transferred into rolling line process and the first pass on direct rolling and conventionally rolling processes were investigated by finite element method.The results show that the average temperature of the 150 mm×150 mm billet within 300 s after being cutting off can still remain more than 1000℃,which is suitable for direct rolling.The reduction in the center of billet via direct rolling is bigger than that through conventional rolling.The results from industrially direct rolling test show a good agreement with the simulated result in terms of temperature field.The tensile test indicates scattered distribution of mechanical properties along the length of bar.After a period of 10-days aging,the change of yield strength and tensile strength along the length direction is in small range of 20 MPa,and total elongation increases obviously in the first ten days.