Hydrogen-induced ductility losses in the heat-affected zone of HT 9 weldments

Results reported previously have demonstrated the deleterious effect of internal hydrogen on the tensile ductility of quench-and-tempered HT 9. The goals of this task are to determine if similar degradation in ductility occurs in the weld heat-affected zone (HAZ) and to study the effect of postweld heat treatment on the hydrogen-charged tensile behavior. The effect of internal hydrogen introduced by cathodic charging on the tensile behavior of simulated HAZ microstructure has been evaluated. The loss in ductility of the HAZ after a postweld heat treatment at 7500C is equivalent to that observed in the quench-and-tempered base material. A postweld heat treatment at 6000C results in tensile ductilities which are inferior to those of the base metal at comparable charging levels