The effect of thermal aging on fracture properties of a narrow-gap Alloy 52 dissimilar metal weld

In nuclear power plants, dissimilar metal welds belong to safety class 1. The effect of thermal aging at 400 degrees C up to 15 000 h on ductile-to-brittle transition (DBT) region was investigated for an Alloy 52 dissimilar metal weld (DMW). The cracks and the notches were placed close to the fusion boundary between the low-alloy steel (LAS) and the weld metal. In previous work for DMWs, the shifts in different DBT temperatures have not been investigated, including reference temperature T0, impact toughness-based T28J and reference temperature for arrest toughness, TKIa. The results show that the T0 reference temperature does not change significantly with aging time, only 10 degrees C, but the shift in T28J is 49 degrees C after 15 000 h. The shift in TKIa is 35 degrees C. The results indicate that the aging mechanism affects more the crack propagation and arrest properties than brittle fracture initiation.

Automated summary

This study investigates the effect of thermal aging at 400 degrees C for up to 15,000 hours on the ductile-to-brittle transition region of an Alloy 52 dissimilar metal weld (DMW). The results show that the T0 reference temperature remains relatively unchanged, with only a 10 degrees C shift, while the T28J temperature increases by 49 degrees C and the TKIa temperature increases by 35 degrees C after aging.