VÝROSTKOVÁ Anna Intitute of Materials Science, Slovak Academy of Sciences

Spoluautoři MACKO Roman, BLACH Juraj, ČIRIPOVÁ Lucia

Sensitivity of Cr-Mo-V structural steels and their weld joints to hydrogen embrittlement has been judged. Base metals of four classes of the steels and their heat affected zones (HAZ) have been investigated in the as received (post weld heat treated - PWHT) and annealed states. Annealing at 565 °C for up to 3000 h was used to simulate the exploitation conditions. Electrolytically charged samples with notch in the base metal and the HAZ were broken using the tensile test. The results have been compared with the respective samples without hydrogen charging. This enabled to evaluate so called embrittlling index EI, and compare the fractures (SEM-scanning elecron microscopy), microstructure (LM-light microscopy) and substructure (transition electron microscopy-TEM) of individaual experimental states with and without hydrogen charging. Even if the values of the EI for 9%-Cr alloys show the highest resistance to hydrogen embrittlement, fractography indicate something different. This discrepancy is later discussed from the viewpoint of micro- and substructure of the experimental states.