Continuous Cooling Sensitization of Type 304 Stainless Steel

This study compares the sensitization of one heat of Type 304 stainless steel by isothermal heat treatments and by continuously cooling through the sensitization region. Predictions of the continuous cooling sensitization (CCS) based upon the isothermal data underestimate the severity of CCS but are within an order of magnitude in their accuracy. Furthermore, the isothermal tests failed to predict a strong influence of the peak temperature of a CCS cycle, when this peak temperature is above that required for isothermal sensitization. CCS is more severe (i.e., occurs at higher cooling rates) when the maximum temperature of the cycle is 800 or 900 C than when it is 1000 or 1100 C. It is also shown that the sensitization observed after the application of more than one thermal cycle cannot be predicted by simply adding the influence of the individual cycles.