- 作者: 洪銘盤;孫文彬
- 作者服務機構: 國立成功大學礦冶及材料科學研究所
- 中文摘要: Zr-2.5wt.%Nb合金管縱長及環狀試片經過氫化處理後,縱長試片於三種不同應變速率 (8.3x10-4sec-1,8.3x10-3sec-1及8.3x10-2sec-1)下分?作25℃至600℃間之拉伸試驗,環狀試片則於拉伸應力(20 ksi )下爐冷至室溫後測其 25℃至400℃間的抗拉性質。 氫含量,溫度及應變速率對縱長試片的抗拉?度及0.2 %降伏?度的影響較全伸長率?小。降伏?度的氫含量依存性 可由氫化物析出硬化及退火軟化的混合效應加以說明。抗拉?度的應變速率感受指數最小?界於300°至400℃之間,可能 與差排次結構的巨變有關。降伏?度在200°至400℃之間變化較小,其因可由間隙型氧原子團的熱激克服及應變時效效應 加以說明。環狀試片的抗拉及降伏?度的變化及大小與縱長試片相差不多,惟其延性在400℃以下因氫化物應力偏向而大量下降。未加及加氫試片的延性變態溫度大約?200℃ 。
- 英文摘要: --
- 中文關鍵字: --
- 英文關鍵字: Both longitudinal and transverse ring specimens of Zr-2.5wt% Nb alloy tube were gaseously hydrided in the range of 15 ppm to 660 ppm. The tensile properties of the longitudinal specimens were determined at three strain rates (8.3 x 10-2, 8.3 x 10-3 and 8.3 x 10-4 sec-1) over the range of 25?to 600蚓. The transverse ring specimens were solution treated and furnace cooled to room temperature under the tensile stress of 20 ksi and finally subjected to the high temperature tensile test in the range of 25?to 400蚓. Tensile strength and 0.2% yield strength of longitudinal specimens depend less strongly on hydrogen content, temperature and strain rate than total elongation. Dependence of yield strength on hydrogen content can be explained by a combined effect of hydride precipitation hardening and anneal softening. The minimum index of strain rate sensitivity in tensile strength is found between 300?and 400蚓, and will be ascribed to a greater change in dislocation substructure with strain rate. The pseudoathermal region of yield strength (200?to 400蚓) will be rationalized in terms of dynamic strain ageing and thermally activated overcoming of interstitial oxygen atom clusters. Variation and magnitude of tensile strength and yield strength in ring specimens are comparable to those of longitudinal specimens. However, ductility is appreciably reduced due to stress orientation of hydrides below 400蚓. Ductility transition is likely to occur at 200蚓 for both unhydrided and hydrided specimens.