Heat treatment for CuCrZr cooling tubes for JT-60SA monoblock-type divertor targets

Higashijima, Satoru; Sakurai, Shinji; Sakasai, Akira

JT-60SA divertor has to receive the maximum heat flux of 15 MW/m for 100 s, and JAEA have developed the monoblock-type CFC divertor target for JT-60SA. For boosting the production yield of the target, CFC cracking due to thermal expansion and contraction of the CuCrZr cooling tube should be suppressed. CuCrZr characteristics strongly depend on the heat treatment, and the target is heat-treated on the manufacturing process of brazing, solution treatment, and annealing. CuCrZr test specimens were heat-treated with the targets, and the strength and the hardness of the specimens were almost the same in the case of the quenching rates of 0.65 C/s and 1.5 C/s around 800 C. It is clarified that the slower quenching rate is acceptable, and the half of the mock-ups at least removed high heat flux of 15 MW/m as required without the CFC cracking.