N-type 6H SiC single crystals irradiated with swift (246 MeV) Kx ions at room temperature (the implantation depth being 21 mum) were investigated by conventional positron lifetime and Doppler-broadening measurements as well as with the application of a slow positron beam. The fluence dependence of the irradiation-induced defects was studied in the 1X10(10) - 1x10(14) ion cm(-2) range. In the fluence and depth range studied, no sign of amorphization (or creation of large voids) was seen in the Kr irradiated crystals. The positron annihilation results were compared with atomic displacement calculations by TRIM. A simple model was used to describe the trapping effect and determine the relationship between the atomic displacement densities and the positron trapping. The 225 ps lifetime of the open-volume defects created suggests that the Vsi-Vc divacancy is the dominant trapping site in the implanted zone.