A surface segregation study in phosphorus-and sulfur-doped type 304 stainless steels

The kinetics of surface segregation of P and S in four purposely doped type 304 stainless steels over the temperature range 550 °C to 850 °C and at aging times up to 12,000 seconds is presented. The saturation coverage of phosphorus is between 30 and 40 at. pct at temperatures greater than 650 °C. Saturation was not attained at 550 °C. The kinetics of the P and S segregation is diffusion controlled and can be described by the surface segregation theory based on a binary system. The results also show that interactions among S, P, and N occur. This interaction affects the kinetic behavior. Site competition of P-N and P-S was also observed.