ABSTRACT

The stress corrosion cracking (SCC) mechanism is investigated in high Si duplex stainless steel in a simulated PWR environment based on TEM analysis of FIB-extracted SCC crack tips. The microstructural investigation in the near vicinity of SCC crack tips illustrates a strain-rate dependence in SCC mechanisms. Detailed analysis of the crack tip morphology, that includes crack tip oxidation and surrounding deformation field, indicates the existence of an interplay between corrosion- and deformation-driven failure as a function of the strain rate. Slow strain-rate crack tips exhibit a narrow cleavage failure which can be linked to the film-induced failure mechanism, while rounded shaped crack tips for faster strain rates could be related to the strain-induced failure. As a result, two nominal strain-rate-dependent failure regimes dominated either by corrosion or deformation-driven cracking mechanisms can be distinguished.

摘要

基于 FIB 提取的 SCC 裂纹尖端的 ​​TEM 分析，在模拟 PWR 环境中研究了高硅双相不锈钢的应力腐蚀开裂 (SCC) 机制。SCC 裂纹尖端附近的微观结构研究说明了 SCC 机制中的应变率依赖性。裂纹尖端形态的详细分析，包括裂纹尖端氧化和周围变形场，表明腐蚀和变形驱动失效之间存在相互作用，作为应变速率的函数。慢应变速率裂纹尖端表现出狭窄的解理失效，这可能与薄膜诱导失效机制有关，而用于更快应变速率的圆形裂纹尖端可能与应变诱导失效有关。其结果，