SIGMA-PHASE PRECIPITATION IN A PHOSPHORUS -CONTAINING TYPE-316 TI STAINLESS-STEEL (Z-6-CNDTP-17-13 STEEL)

The formation of the intermetal[ic cr compound was studied in samples of a stainless steel of the 316 Ti type having a phosphorous content o f 0.15 % in mass (Z 6 CNDTP 17-13) that had undergone precipitation tr eatments at 600, 650, 700 and 800 degrees C for dwell times as high as 4000 h. The results observed show that an addition of 0.15 % P, in ma ss, decreases the precipitation of the sigma phase in this material, T his fact may be explained by a precipitation of other phases, notably carbide M(23)G(6) and the intermetallic compounds eta and chi, whose f ormation occurs before the sigma's. However, the abundant precipitatio n of carbide M(23)C(6), observed in this alloy, seems to be the main c ause of delay in nucleation of the sigma phase.