A Tensile test of vacuum fired titanium

Suganuma, Kazuaki ; Hikichi, Yusuke; Ogiwara, Norio; Sukenobu, Satoru*

Pure Ti is adopted as a material for ducts and bellows at the proton accelerator 3 GeV-RCS in J-PARC project, because of its small residual radioactivity. We intended to apply vacuum firing to reduce the hydrogen content in the Ti. The firing at temperatures higher than 550C was effective in reducing the hydrogen content in the Ti. At the same time, we have measured the mechanical properties because grain growth leads to decrease in mechanical strength. Even after treatment at 750C for 8 hr, the decreases in tensile and yield strength were so small (10%) that we have no anxiety about the reduction of mechanical strength. Based on the above results, to reduce the hydrogen content, the Ti bellows and ducts for the RCS have been vacuum fired at 650C for 8 hr and at 750C for 8 hr, respectively.