对中子辐照前后的Zr-4合金包壳管进行了低周疲劳试验,以研究其在辐照前后的低周疲劳行为变化。通过试验数据拟合出了未辐照试样的循环应力-应变特性和Coffin-Manson关系曲线,得出了中子辐照对Zr-4合金包壳管低周疲劳行为的影响。并对管材的低周疲劳断口进行扫描电镜(SEM)分析,讨论Zr-4合金管材的低周疲劳断裂机制。研究结果表明辐照后的Zr-4管材脆化比较严重,中子辐照不改变Zr-4管材循环软化的特性,使其强度系数和应变硬化指数变大,材料常数变小,疲劳寿命大大降低。

The low cycle fatigue property of the Zr-4 cladding before and after the neutron irradiation is investigated in this paper. The stress-strain curve and the Coffin-Manson relation of the pre-irradiation specimens are first obtained. Then an estimation of the effect of the neutron irradiation on the low cycle fatigue property of Zr-4 cladding is obtained. The fatigue crack microstructure is analyzed and the mechanism of the fatigue is discussed. It is shown that the Zr-4 tube sees a serious irradiation-embrittlement. Both non-irradiated and irradiated specimens show cyclic softening. The strength coefficient and the hardening exponential are increased, the material constant is decreased and the life of the Zr-4 tube is reduced after the iradiation.