X-RAY FRACTOGRAPHY STUDIES ON AUSTENITIC STAINLESS-STEELS

In this investigation, the fracture surfaces of SS 304 and SS 316 aust enitic steels were analysed using the X-ray fractography technique. In both cases, a decrease in the austenite content was observed at the f racture surface as a result of deformation induced martensite, indicat ing a linear relation with K-max within the stable crack growth region . The presence of this martensite was found to be confined to a very t hin layer close to the fracture surface. The magnitudes of the residua l stress (sigma(r)) as well as the profile breadth (B) as a function o f K-max in martensite were found to be higher than in austenite, with greater differences in SS 304 than in SS 316. In both the steels a gra dual decrease of sigma(r) with depth below the fracture surface was no ticed. While a gradual decrease of B was noticed in SS 304, a shallow minimum was noticed at a depth of about 100 mu m in SS 316. (C) 1996 E lsevier Science Ltd.