镍基合金应力腐蚀裂尖氧化膜力学特性分析

裂纹尖端氧化膜形成与破裂是核电站压力容器高温水环境中镍基合金材料应力腐蚀开裂(SCC)的主要过程之一。由于应力腐蚀裂纹尖端形貌和扩展方式的特殊性,本研究利用ABAQUS有限元软件的子模型技术,在微观尺度下对由裂尖氧化膜和基体金属共同构成的应力腐蚀裂尖应力应变场进行了分析。结果表明,SCC裂尖氧化膜前端沟形裂纹的存在,会造成氧化膜中应力和应变的很大变化,且随着沟形裂纹的长度增加,这种变化越加明显;另一方面,与氧化膜中应力相比,塑性应变对裂尖形貌变化更加敏感,从一个侧面说明,裂尖塑性应变是研究SCC裂尖氧化膜形成与破裂比较理想的力学参量。

Analysis on Mechanical Property of Oxide Film in Stress Corrosion Cracking Tip of Nickel-based Alloys

It is one of the basic processes that the oxide film form and rupture in the tip of stress corrosion cracking (SCC) of nickel-base alloys in high temperature water environment of the nuclear pressure vessel. Because of the particularity of the propagating mode and morphology of the tip of SCC, the stress and strain in the tip of SCC constituted of the tip oxide film and base metal was simulated and analyzed under the micro scale based on the sub-model technology in ABAQUS software. The results show that the groove-type crack significantly affects the stress and the plastic strain in the oxide film at the SCC crack tip, and the longer the groove-type crack is, the more obvious the effect is. On the other hand, compared with stress, the plastic strain is more sensitive to the morphology of the tip of SCC; therefore, the plastic strain should be an appropriate mechanical parameter to investigate the oxide film character in the SCC crack tip