超临界温度下Inconel 617B的力学行为

MECHANICAL PROPERTIES OF INCONEL 617B ALLOYAT ULTRA-SUPERCRITICAL TEMPERATURE

针对Inconel 617B合金,分别完成了常温、700℃下单轴拉伸试验和等幅应变疲劳试验。基于漏斗试样有限元辅助测试(Finite-element-analysis Aided Testing,FAT)新方法获得了Inconel 617B合金在两种温度下直至破坏的单轴拉伸真实应力-应变试验关系,给出了材料临界破断应力、破断应变、应力应变描述新方程与参数;研究了两种温度下Inconel 617B合金的循环应力演化行为、循环本构关系、应变幅与寿命关系和超超临界服役温度效应。研究结果表明,超超临界温度使Inconel 617B合金的弹性模量、屈服强度、极限强度、临界破断应力、破断应变和试样颈缩后漏斗根部横截面中心点应力三轴度等力学性能降低显著;提出的真实应力-应变关系新方程对FAT获得的结果曲线描述良好;有限元辅助分析得出,试样漏斗根部横截面中心的应力三轴度最大,700℃下破断时最大应力三轴度远低于常温结果;Inconel617B合金在两种温度下均表现出明显的循环硬化特征,超超临界温度使得Inconel 617B合金的循环稳定寿命比例明显减小、抗疲劳性能显著降低;Manson-Coffin模型可良好描述两种温度下Inconel 617B合金的低周疲劳试验寿命结果。

A group of tests on uniaxial tension and low cyclic fatigue under constant strain amplitude at room temperature and 700 ℃ have been carried out for ultra-supercritical Inconel 617B alloy. Based on new method of finite-element-analysis aided testing on funnel specimen,we can get uniaxial tensile true stress-true strain curves until fracture. Then,fractured stress and strain,described equation of the true stress-true strain curves and parameters of the equation at two temperatures are obtained. At last,Evolutive behavior of cyclic stress,cyclic constitutive relationships,relationships between strain amplitudes and cyclic lives,ultra-supercritical temperature effects are studied. The results show that,ultra-supercritical temperature makes the elastic modulus of Inconel 617B,yield strength,ultimate strength,critical breaking stress,breaking strain and stress triaxiality of centre point on funnel root transversal surface after specimen necking decrease significantly. The curves obtained by FAT are well described by the new equation of the true stress-strain relationship. The finite-element-analysis shows that stress triaxiality of centre on funnel root transversal surface is the largest than other points,the maximum of fractured stress triaxiality at 700 ℃ is much lower than room temperature. 617B Inconel alloy performs obvious cyclic hardening characteristics at two temperatures. The cyclic stable life percent of 617B Inconel alloy reduces greatly and the anti-fatigue property weakens significantly under ultrasupercritical temperature. Manson-Coffin life-prediction model can describe the low cyclic fatigue life under two temperatures very well.