DZ408合金低周疲劳行为

Low-cycle Fatigue of Directionally Solidified Superalloy DZ408

研究了DZ408合金在950℃,1000℃和1050℃,应变比为0.05条件下的低周疲劳性能。结果表明:平均应变为正时,非对称循环应变控制会产生平均应力松弛现象,且随着温度与应变幅的增大,平均应力松弛速率增大;在950℃,1000℃和1050℃时,材料具有Massing特性,采用修正的SWT模型能很好地预测不同温度下应变比为0.05的低周疲劳寿命,且给出了修正SWT模型参数随温度变化的关系式Δεt2σmax=(-38.9+0.101T)N(0.96-0.0014T)。

The total strain-controlled low cycle fatigue（ LCF） behaviors of directionally solidified（ DS） superalloy DZ408 at 950 ℃,1000 ℃ and 1050 ℃ for R = 0. 05 were investigated. The results of LCF tests indicate that the mean stress relaxation is occurred under asymmetric straining. The rate of mean stress relaxation is increased with the increase of temperature and strain amplitude. The alloy has Massing characteristic at 950 ℃,1000 ℃ and 1050 ℃ for R = 0. 05. All the LCF data obtained under various temperatures are well correlated by the modified SWT approach for lifetime prediction,and also the relationship between temperature and parameter of modified SWT model are obtained.