The  process  of thin  slab  produced  by  FTSR(Flexible  Thin  Slab  Rolling)process  has  been  simulated  by Gleeble-3500  thermal  simulation  machine

and  the  high  temperature  plasticities  of  slab  of  steel  SS330(0.06%C)and  steel SS400(0.20%C)600～1350  ℃  were  tested

Results  showed  that  the  high  temperature  plasticity  of  steel  SS400  at  700~ 900 ℃ was high than that of steel  SS330;the high temperature plasticity decreasing of steel  SS400 due to segregation and accumulation of sulphide and oxide at boundary of columnar crystal caused inner cross crack formation in slab. With con trolling   sulphur  content  in   steel  decreasing  to  0.010%  from  0.015%

total  oxygen  content  to  30×10

-6

from  45×10

-6

superheating  degree  of  molten  steel  to 20~35℃  from 30~50℃

Mn/S  in  steel  ≥60  a

nd  modifying  slab  casting  speed  to 3.0~4.5  m/min  from  original 2.5~6.0  m/min  with  reasonably  controlling  secondary  cooling  water  amount

the  thin  slab inner cross crack was avoided effectively.