敏化之304型不銹鋼在模擬沸水式反應器環境中的疲勞裂縫成長行為

Fatigue Crack Growth Behavior of Sensitized Type 304 Stainless Steel in Simulated Boiling Water Reactor Environments

本論文使用破壞力學標準緊緻拉伸試片，研究電化學電位再活化值為30 C/cm2的敏化304型不銹鋼，在288℃之模擬沸水式反應器環境中的疲勞裂縫生長速率行為。試驗以週期式或梯形負荷條件來進行。試驗環境為含有200 ppb溶氧的正常水化學或含有10 ppb溶氧與160 ppb溶氫的加氫水化學之純水。結果發現：敏化之304不銹鋼在高溫水中的電化學腐蝕電位與溶氧及溶氫量有密切的關係。然而，不論負荷形式為週期式或梯形，加氫水化學均無法減緩裂縫成長速率。實驗量測到的裂縫成長速率均無法被ASME法規第十一節之附錄C的參考曲線所涵蓋，而所有數據卻均可被JSME之裂縫估算法規所規範。最後，結果亦顯示阿岡諾國家實驗室對於不銹鋼在高溫純水中的裂縫成長速率之預測模型的準確性高於奇異公司所發展之預測模型。

The fatigue crack growth rate (FCGR) behaviors of sensitized Type 304 stainless steel (304 SS) with an electrochemical potentiokinetic reactivation (EPR) value of 30 C/cm2 was investigated using fracture mechanics-type standard compact tension (CT) specimens in simulated boiling water reactor (BWR) environments at 288oC. Tests were performed under either cyclic or trapezoidal loading conditions. Test environments were pure water either with 200 ppb dissolved oxygen (DO) under normal water chemistry (NWC) conditions or with 10 ppb DO plus 160 ppb dissolved hydrogen (DH) under hydrogen water chemistry (HWC) conditions. The electrochemical corrosion potential (ECP) of sensitized 304 SS in high-temperature pure water was found to be closely related to the amounts