The tensile  strength (Rm) and  reduction  of  area(Z)of  250  mm×2100  mm  cast  slab  of  steel  CCSD36 (%:0. 14C

1.31Mn

0.02Nb

0.02Ti) at   600～1350  ℃   has   been   measured   by   using   Gleeble- 1500   thermal   simulation testing machine and the structure of fracture of tensile specimen tested at 600～1150 ℃ was analyzed. It was obtained that the  steel had high plasticity  at  1300～900  ℃

of which the Z value  at this temperature range was ≥80%

and the Z value of steel decreased  to 52%～55% at  850～720  ℃(Ⅲ  brittle  zone)

therefore  the  strengthening  temperature  of cast  slab  of steel  CCSD36  should  be  ≥900  ℃.