Fracture Toughness of Irradiated HT-9 Weld Metal

Fracture toughness tests were performed at 93, 205, 316, and 427°C using electropotential techniques on HT-9 weld material irradiated to a fluence of 2.35 × 10²² n/cm² (E>0.1 MeV) at 390°C. Testing of welds irradiated at 450, 500, and 550°C was performed at 205°C. Test results were analyzed using the J-integral approach. It was found that the initiation fracture toughness of these HT-9 welds increased slightly, while the tearing modulus decreased significantly after irradiation to a fluence of 2.35 × 10²² n/cm². In addition, results showed that irradiation temperature had little effect on the initiation fracture toughness of HT-9 weld metal. The specimens were examined by scanning electron microscopy after the test in order to understand the fracture process in this weld material.