Zr－4合金的低周疲劳行为

LOW CYCLE FATIGUE PROPERTIES OF ZIRCALOY-4

研究了６２０℃×１ｈ再结晶状态Ｚｒ－４合金在室温（ＲＴ）、４００℃和６００℃下对称拉－压低周疲劳行为，不同温度下Ｚｒ－４合金的循环应力－应变曲线均位于单调拉伸曲线上方，表现为循环硬化特征。疲劳寿命曲线测试结果表明，随着试验温度升高，疲劳寿命降低，特别在低应变幅区域。断口分析表明：ＲＴ下Ｚｒ－４断口形貌以浅的韧窝和辉纹为主；４００ ℃下出现了许多二次裂纹；６００℃下则为规则排列的“之”字形裂纹．分别采用Ｃｏｆｆｉｎ－Ｍａｎｓｏｎ法和循环滞回能法估算了Ｚｒ－４的疲劳寿命。

ow cycle fatigue properties of zircaloy-4 at 620℃×1h recrystallized condition were investigated at RT,400℃ and 600 ℃. The cyclic stress- strain curves laid above the monotonic ones for zircaloy-4 at different testing temperances,thus the cyclic hardening character was displayed. The testing results showed that the fatigue lifetime was decreased as the testing temperature decreased, specifically at lower cyclic strain ranges. The fracture surface analysis indicated that the typical morphology was shallow dimples and stripes at RT, many micro- cracks and dimples at 400, many zigzag cracks in regular arrangement at 600 ℃. The fatigue lifetime of zircaloy-4 was evaluated with Coffin-Manson law and cyclic strain energy method, respectively.