Positron Annihilation Studies of a Pressure Vessel Steel

Two different methods of positron annihilation measurements (lifetime spectrum and Doppler broadening) have been applied on different grades of the JRQ-steel. Doppler broadening result show distinct differences in dependence of steel grade where lifetime measurements exhibit only minor differences. Due to the annealing heat treatment the density of lattice defects is reduced in the so called 'aged' specimen compared with the state 'as delivered' even if new martensite is produced by quenching after annealing.