Reduction of hydrogen content in pure Ti

Ogiwara, Norio; Suganuma, Kazuaki ; Hikichi, Yusuke; Kamiya, Junichiro   ; Kinsho, Michikazu  ; Sukenobu, Satoru*

Pure Ti is adopted as a material for ducts and bellows at the 3 GeV-RCS in J-PARC project, because of its small residual radioactivity. In the particle accelerator, the H outgassing due to ion impact is often dominant gas release. As the reduction of hydrogen content probably leads to the suppression of ion induced desorption, we intend to reduce the hydrogen content in the Ti by in-situ vacuum baking. First of all, thermal desorption behavior and the change in hydrogen content have been investigated. The vacuum firing over than 550C is effective to reduce the hydrogen content in the Ti. The mechanical properties have been also monitored because a grain growth leads to the decrease of mechanical strength. Even after the treatment at 750C for 12 h the decreases in tensile and yield strength are so small (10%) that we have no anxiety about the reduction of mechanical strength. Based upon this study, the vacuum firing has been applied for the RCS machine.