锆-4合金的疖状腐蚀

On the Nodular Corrosion of the Zircaloy-4

对不同状态的锆-4合金管材进行了高温蒸汽腐蚀研究。经400℃预膜和未预膜的样品在460℃/10.3 MPa的蒸汽中进行腐蚀试验,结果表明:未预膜的样品迅速腐蚀,而预膜处理延缓了疖状腐蚀的产生;不同加工工艺的样品的腐蚀结果截然不同。挤压前进行β淬火使Zr-4合金的抗疖状腐蚀性能得到改善,应变时效处理后的Zr-4合金管材具有良好的抗疖状腐蚀性能。疖状腐蚀的敏感性与合金的组织状态密切相关,取决于合金中的第二相粒子的数密度、平均粒子大小和基体中溶质元素的含量。

High temperature steam corrosion has heen investigated for Zircaloy-4 tubes in different conditions in this paper.Samples with pre-filming at 400℃ and without pre-filming are tested in the steam of 460℃ and 10.3MPa.The test results show that the samples without pre-filming were rapidly corroded,and the pre-filming treatment can postpone the initiation and growth of nodular corrosion.The effects of process on nodular corrosion have been obtained from the corrosion test results. Nodular corrosion resistance of Zircaloy-4 can be improved by β-quenching before extrusion.The Zircaloy tubes after strain-aging have the best nodular corrosion resistance.The relations between nodular corrosion and alloy structures have been also analyzed in this paper.It is found that sensitivty of Zircaloy-4 to nodular corrosion depends on the number density,the size of second phase particles in alloy and the content of solute elements in matrix.