a retired Consultant, Pittsburgh, PA
When Type 304 stainless steel is sensitized by a thermal treatment in the range of 400 to 850°C, intergranular attack will occur upon subsequent exposure to certain media. Interest in the sensitization behavior of Type 304 has been rekindled by the recurrent problem of pipe cracking in boiling water reactors, and the subject is of major importance to the electric power utility industry. In many practical situations, such as welding, sensitization is best studied by continuous cooling through the sensitizing temperature range wherein the variables are the peak temperature reached and the cooling rate in contrast to temperature and time of the isothermal hold which has been the customary practice. This report will focus on the importance of continuous cooling sensitization in certain heats of Type 304 with changing section size. A review of the test methods that assess intergranular corrosion and the effort to quantify degree of sensitization upon Jominy testing of bar, strip, and pin specimens or Gleeble-type testing of small rods will be presented. The major influence of carbon content and the effects of other elements will be discussed along with material remedies and suggestions for future work.
Paper ID: JTE10326J