新锆合金包壳的碘致应力腐蚀研究

Iodine Induced Stress Corrosion of New Zirconium Alloy Cladding

研究了应力腐蚀裂纹生长与碘浓度、温度及晶粒尺寸的关系,利用直流电压降测量裂纹长度的方法,对不同成分和不同取向的新锆合金,在不同的碘浓度和温度下进行了应力腐蚀裂纹生长的监测试验,并对应力腐蚀断口形貌进行了观察。结果表明:对于同种材料在相同的碘浓度下,随着温度的升高,裂纹的扩展速率加快。对于同种材料在相同的温度下,在饱和碘浓度前,随着碘浓度的增大,裂纹的扩展速率加快,达到饱和碘浓度时,对裂纹扩散速率的影响不大。晶粒尺寸大小对裂纹扩展速率也有影响。

In order to systematically study the dependency of stress corrosion crack growth on iodine concentration, temperature and grain size the methodology of direct current potential drop (DCPD) had been utilized for measuring crack length in the tests of stress corrosion crack growth at different iodine concentrations and temperatures with zirconium alloys of different compositions and orientations. Observations of fracture morphology were carried out. The results showed that for the same material and the same iodine concentration, the rate of crack propagation increased with increasing temperature. For the same material and the same temperature, the rate of crack propagation increased with increasing iodine concentration within the scope of 40 - 60℃. The iodine concentration at 110℃ had no any effect on the rate of crack propagation. Grain size had some effect on the rate of crack propagation.