Sunhurov B. Effect of radiation-induced microstructural defects on processes of accumulation of hydrogen and hardening of SS316 austenitic steel

The dissertation is devoted to the determination of physical law of the trapping and accumulation of hydrogen, mechanisms of SS316 steel hardening, and the influence of radiation defects and implanted helium on these processes. The evolution of SS316 steel microstructure, temperature desorption intervals and the depth distribution of hydrogen isotopes in steel after implantation in a wide range of doses and temperatures have been investigated. The main types of defects and the thermodynamic parameters of the interaction of trapped hydrogen with them are determined. It has been established that bubbles of an inert gas or stress fields near them are strong traps of implanted deuterium. The dependence of steel hardening on irradiation conditions is investigated. It is shown that the hardening effect is primarily due to the conservative nature of the Frank loops, which impede motion of dislocations. Helium and hydrogen enhance hardening by 20-30% at concentrations of more than 1 at.%. These two factors - the Frank loops and gas impurities account for a 1.8-fold increase in hardening and yield strength.