GH3044的高温低周疲劳性能研究

Investigation on Low Cycle Fatigue Properties of Superalloy GH3044 at Elevated Temperature

研究了镍基高温合金GH3044在600℃下的低周疲劳性能,分析了合金的循环应力-应变和应变-寿命关系,利用Manson-Coffin方程、三参数幂函数方程和拉伸滞后能模型对寿命数据进行回归分析。结果表明,合金的循环应力响应行为在600℃时,呈现明显的循环硬化特征,原因在于循环变形过程中位错之间以及位错与析出相之间的相互作用;从试样的疲劳断口形貌发现,裂纹主要萌生于试样表面处,裂纹形成后垂直于加载轴方向扩展,断口呈韧窝断裂特征;在合金的低周疲劳寿命预测研究中发现,拉伸滞后能模型的寿命预测结果无论从标准差,还是分散带方面比较都比Manson-Coffin方程、三参数幂函数方程的预测精度好。

Low cycle fatigue（LCF）tests of nickel-base superalloy GH3044 were conducted under total axial strain control at 600℃. The specimens were tested under fully reversed strain. The life prediction capability of Manson-Coffin equation, Three-parameter power function and Ostergren model were evaluated by the LCF data. The results indicated that the alloy exhibited cyclic hardening behavior at 600℃, which could explain by the interactions between dislocations or dislocation and precipitates during cyclic deformation. The fatigue parameters were obtained by analyzing its cyclic stress-strains curves and strain-life curves. SEM observations indicated that LCF cracks initiated predominantly on the surface of specimen. Once initiated, cracks would propagate perpendicularly to the loading direction and the specimens exhibited dimple fracture. The results of life prediction showed Ostergren model gave better results with the smaller scatter band and standard deviation than Manson-Coffin equation and three-parameter power function.