Cu-Cr-Zr合金の機械的特性に及ぼす酸化および水素添加の影響

抄録

Cu alloys used for recent rocket combustion chambers are exposed to severe conditions, i.e., high temperature environments with oxidizing followed by reducing. Therefore, it is very important to understand the effects of such severe environments on their mechanical properties for maintaining their integrity for a long time. In this study, in order to investigate the effect of internal oxidation on mechanical properties, Cu-Cr-Zr alloy was subjected to the oxidation test at 825℃ for 15h and then the small punch (SP) test specimens (φ3.0×0.25t[mm]) were removed from the resultant internal oxidation layer. Some of SP specimens were exposed in the high temperature and high pressurized hydrogen gas atmosphere (7.6MPa, 600℃, 24h) for hydrogen-charging. The SP tests were applied to the oxidized and the hydrogen-charged specimens at the temperatures ranging from room temperature to 600℃. Experimental results revealed that Cr and Zr were preferentially oxidized along grain boundaries and Cr precipitates were also selectively oxidized in the grains by the internal oxidation. The strength and ductility of oxidized specimen gradually decreased with increasing testing temperature accompanying intergranular brittle fracture, although the internal oxidation had almost no influence on the mechanical properties at room temperature. Additionally, the degradation of mechanical properties was more pronounced by the hydrogen-charging, especially, in room temperature.