Cu-3Ag-0.5Zr合金的高温低周疲劳性能研究

High Temperature Low Cycle Fatigue Properties of Cu-3Ag-0.5Zr Alloy

研究了Cu-3%Ag-0.5%Zr合金在800K条件下的高温低周疲劳性能。对循环应力响应行为及循环应力-应变行为进行了分析,给出了Cu Ag Zr合金的疲劳参数,并根据试验数据拟合出了疲劳寿命曲线和方程。结果表明,Cu Ag Zr合金的位错密度较低,循环应力响应行为表现出循环软化特征,合金低周疲劳曲线方程为Δεt/2=0.003(2Nf)-0.1104+0.14(2Nf)-0.7792,合金具有较低的弹性应变幅和较低的过渡疲劳寿命,塑性对疲劳寿命起决定性作用。疲劳裂纹起源于试样表面,且存在有多个裂纹源,有大量微小孔洞存在,孔洞连接萌生裂纹,合金高温断裂方式为穿晶韧性断裂。

Low cycle fatigue tests of Cu-3% Ag-0.5% Zr alloy were conducted at 800 K in air. Cyclic stress response behavior and cyclic stress-strain behavior were analyzed. The fatigue parameters of Cu Ag Zr alloy, the fatigue life curve and equation was filt out according to the experimental datas. The results show that Cu Ag Zr alloy has low dislocation density. The cyclic stress response behavior exhibit cyclic softening characteristics. The low cycle fatigue curve equation： Δεt/2=0.003（2Nf）-0.1104＋0.14（2Nf）-0.7792. The alloy has lower elastic strain amplitude and lower transition fatigue life. The plasticity plays a decisive role on the fatigue life. Fatigue cracks originate in the surface of the specimen, and there is more than one crack source, the presence of a large number of tiny holes appear. The holes are connected to crack initiation. The high temperature fracture mode of the alloy is transgranular ductile fracture.