The continuous oxidation behaviour of a B445J1M ferritic stainless steel(FSS)was investigated in humid atmosphere containing 18%water vapour in the temperature range of 1000 to 1200℃.The isothermal oxidation behaviour of indefinite chill(IC)roll material was also studied in both dry and humid atmospheres at a temperature range of 550 to 700℃.The results indicate that the formation of Cr-rich oxide follows a parabolic law over time before breakaway oxidation occurs,and breakaway oxidation occurs at 1150℃ for the B445J1M steel.Temperature of 1150℃ is critical for the B445J1M steel that breakaway oxidation takes place and more oxides begin to form.In the dry air,the oxidation kinetics of the IC roll show that the mass gain raises gradually with the increase of temperature until 650℃,and the mass gain at 700℃ is lower than that at 650℃.In the humid atmosphere,however,the mass gain shows a linear trend and obviously goes up with the increase of oxidation temperature.The oxide scale formed in humid atmosphere adheres firmly to the matrix,whereas the oxide scale generated in dry air tends to peel off.In order to solve the sticking problem of FSS B445J1M,reheating temperature higher than 1150℃ before hot rolling and practical application of IC work rolls are suggested.