摘要
通过进行具有拉伸保持、压缩保持和拉－压保持的全反向总应变控制的低周疲劳实验，对镍基高温合金ＧＨ４０４９的蠕变－疲劳交互作用行为进行了系统的研究。结果表明，在较高的总应变幅下，合金首先发生循环应变硬化而后则发生软化直至断裂，而在低的总应变幅下则表现为循环稳定。由于压缩应变保持和拉－压应变保持的介入，合金的疲劳寿命将显著降低，但拉伸应变保持对疲劳寿命的影响则取决于总应变幅。拉伸保持或压缩保持时将分别产生平均压应力或拉应力。扫描电镜断口观察结果表明，裂纹萌生和第Ⅰ阶段的扩展均为穿晶形式，而第Ⅱ阶段的裂纹扩展则主要为沿晶形式。此外，利用线性累积损伤法则对蠕变－疲劳寿命进行了预测。
Creep fatigue interaction behavior of nickel based superalloy GH4049 is studied by performing fully reversed total strain controlled low cycle fatigue tests with equal hold in tension and compression,hold in tension or in compression.At higher strain amplitudes, the alloy exhibits cyclic strain hardening followed by softening while a stable cyclic stress response is shown at low strain amplitudes.A significant reduction in fatigue life is observed with hold time in compression or in both tension and compression.The influence of tensile hold on fatigue life is mainly related to the imposed total strain amplitudes.The opposite mean stress develops during tensile and compressive hold tests.Crack initiation and stage Ⅰ growth is transgranular,but crack growth in stage Ⅱ is primarily intergranular.In addition,a linear damage summation method is chosen to predict creep fatigue lifetime.
出处
《航空材料学报》
EI
CAS
CSCD
1998年第3期1-7,15,共8页
Journal of Aeronautical Materials
关键词
蠕变-疲劳
交互作用
镍基
高温合金
寿命预测
creep fatigue interaction, nickel based superalloy, lifetime prediction
