Positron Annihilation and Complementary Studies of Stainless Steel Exposed to Sandblasting at Different Angles

Defect studies in subsurface zone in stainless steel 304 AISI samples exposed to sandblasting were performed using positron annihilation spectroscopy techniques. Samples were sandblasted with a different impact angle. Conventional experiments based on positrons emitted directly from the radioactive source allowed us to detect vacancies on the dislocation edges in all samples; however, the total depths of subsurface zones depended strictly on the impact angle, i.e., 35 lm for impact angle of 90 degrees and about 12 mu m for 30 degrees. The complementary methods such as SEM and optical profilometry revealed also dependencies between the impact angle and roughness of the surface which are not observed in the variable energy positron beam examinations.