Structural regions such as CGHAZ, FGHAZ, ICCGHAZ and SRCGHAZ in steel welded joints are characterized. Based on the simulation technique, different HAZs in 13HMF steel after long-lasting service were simulated, imitating the influence of multiple welding thermal cycles (multilayer welding). Results of notch toughness and hardness tests as well as microstructure examination of individual simulated HAZ regions in 13HMF steel have been discussed.