1996 Volume 82 Issue 11 Pages 881-886
Change of temperature and thermal stress which were generated in MgO-C bricks 1080 mm, 540 mm and 270 mm long was studied under a temperature transition simulated to BOF operation. Thermal and mechanical properties of samples without metal and samples with 3% Al, after heat treating many times at high temperature, were measured at the temperature for data to be used for FEM (Finite Element Method) calculation. (1) Data of thermal expansion coefficient and elastic modulus which were applied for calculation at the start of operation were different from those applied in the middle of operation. (2) In the middle of operation, the temperature regularly changed and large stresses were generated in the fixed inner range from hot face regardless of the brick length. However, the temperature did not change and stress was nearly zero outside the fixed inner range. (3) Large stress which produced a crack was generated at the start of operation and reoperation. (4) A crack of samples with 3% Al could be formed at a closer point to the hot face than that of samples without metal, because the elastic modulus of the former was higher than that of the latter.