Sekundární vytvrzení homogenních svarových spojů oceli T24

Abstract

Theoretical part is devoted to modified 2.25 %Cr steels developed for components of modern thermal power plants. These steels are widely used for production of water walls in boilers. The attention has been devoted to welding of steels for energy industry, weldability of T24 steel and basic reasons for secondary hardening of welds. Experimental part of diploma thesis deals with structure and hardness changes in homogeneous T24 welds after annealing at 460 °C (simulation of technological annealing of boilers) and after subsequent annealing at temperature of 530 °C for 10 and 1 500 hours (simulation of start – up procedure of boilers). The results demonstrate that if post weld heat treatment of homogeneous T24 steels is not applied, a significant secondary hardening of weld metal and especially of coarse grained part of heat affected zone can be expected during the start up procedure.