氢含量对新锆合金室温循环变形行为的影响

Influence of Hydrogen Content on Cyclic Deformation Behavior of New Zirconium Alloy at Room Temperature

NZ2是我国自行研制的具有自主知识产权的新型Zr-Sn-Nb系锆合金,其堆外性能,尤其是耐蚀性能已达国外新合金同等实验条件下的相同水平,是十分具有应用前景的新锆合金。锆在反应堆中服役时会与冷却剂反应而吸氢,从而使锆合金的性能降低,导致失效。通过应变控制的对称拉-压(εR=εmin/εmax=-1)疲劳实验研究了不同氢含量(未渗氢,200,450,730μg·g-1)对NZ2新锆合金的室温低周疲劳性能以及氢含量对材料循环硬化及软化的影响,发现随着氢含量的增加,相同应变下材料的低周疲劳寿命下降,但达到某一饱和值的时候材料的低周疲劳性能不再降低,随着氢含量的增加,材料有循环软化趋势,NZ2锆合金含氢试样比无氢试样更容易出现循环软化现象。

NZ2 is a new type of Zr-Sn-Nb zirconium alloy with good out-of-pile performance, which is an independent intellectual property alloy of China. As the burn-up proceeds, an oxide and subsequent hydrogen caused by a waterside corrosion were generated in the cladding, which decreased the initial ductility of the cladding. Such oxide and hydrogen acted as a negative effect on safety of the cladding. The effect of hydrogen content （natural hydrogen content, 200, 450, 730 μg·g^-1） on the low cycle fatigue （LCF） behavior of NZ2 alloy at room temperature were investigated using fully-reversed tension-compression loading under strain control （εR = εmin/εmax = - 1）. The resuits showed that hydrides would shorten the LCF life of the NZ2 alloy, but the LCF life would decrease no longer, when the hydrogen content reached a certain value. The effect of fatigue softening was found in the tests. In addition, the phenomenon of cyclic softening for the samples containing hydrogen was more easy to appear than that for the sample containing no hydrogen under the same test conditions.