500℃过热蒸汽中锆合金不同取向晶粒表面 氧化膜应力状态的模拟研究

The Simulation Study of the Stress State of Zirconium Alloy Grains with Different Orientations at 500 °C Superheated Steam

摘要:

腐蚀各向异性是锆合金腐蚀过程中需要重点关注的一个问题且对于研究锆合金腐蚀机理有着重要的意义。本文基于有限元方法模拟了500 ℃/10.3 MPa 过热蒸汽中锆合金(11-20)取向晶粒及(0001)取向晶粒表面氧化膜的应力状态。模拟结果表明：锆合金两种取向晶粒表面氧化膜的应力分布规律一致，氧化膜应力呈梯度分布，在氧化膜厚度方向上，应力自氧化膜内表面向氧化膜外表面递减；氧化膜内应力随氧化膜厚度的增加均呈先减小再增加再减小的趋势，在氧化膜达到10 μm后，应力不再有明显的变化趋势；(11-20)取向晶粒及(0001)取向晶粒表面氧化膜应力大小及应力梯度存在明显的差异，这也是其耐腐蚀性能不同的原因之一。

Abstract:

The anisotropic oxidation characteristics is an important issue that needs to be focused on during the corrosion process of zirconium alloys, and it is of great significance for studying the corrosion mechanism of zirconium alloy. Based on the finite element method, the stress state of the oxide film of zirconium alloy with (11-20) oriented grain and (0001) oriented grain in superheated steam at 500 °C/10.3 MPa was simulated in the paper. The simulation results show as follows: The change of stress distributions of the oxide films on zirconium alloy with (11-20) oriented grain and (0001) oriented grain exhibits the same trend with the increase of the oxide film thickness. The stress of the oxide film is distributed in a gradient. And in the thickness direction of oxide film, the stress decreases from the inner surface to the outer surface of the oxide film. The compressive stress in the oxide film decreases first, then increases and then decreases with the oxide film thickness increasing, and after the oxide film reaches 10 μm, the stress no longer has a significant change trend. There are obvious differences in the stress magnitude and stress gradient of the oxide films on the surfaces of (11-20) oriented grain and (0001) oriented grain, which is one of the reasons for the different corrosion resistance.