隨機負荷下鋼鐵在充氫環境中腐蝕疲勞之研究

Corrosion Fatigue of Steels in Hydrogen Charging Environment under Random Loading

本研究目的在模擬含疲勞裂縫之鋼鐵構件置於氫脆破壞環境中，承受接近實際應力狀況之不等振幅負荷時破壞之情形。實驗中先製造出隨機訊號，以模擬構件在實際應用時所受到之隨機負荷，並給予電解充氫之環境，探討究其腐蝕疲勞裂縫成長之行為。在未來研究，將以統計方法評估疲勞壽命，建立一套便利的預估模式，而可不經實驗分析直接估算疲勞壽命。使工程上之構件設計，提供一安全、經濟的方法。本研究初期，成功地設立一完善的隨機負荷疲勞試驗系統。充氫環境中疲勞裂縫成長速率明顯比空氣中提升不少。同樣在充氫環境中，由於隨機負荷中有較小的振幅，較不能促進裂縫成長，所以在相同的裂縫成長範圍內，隨機負荷之疲勞壽命相較常振幅之疲勞壽命來得長。

The objective of this project is to study the corrosion fatigue crack propagation (CFCP) behaviors of AISI 4130 steels under random loading. Electrolytic hydrogen charging environment was used in all tests. In addition to experiment evaluation, a cheap and accurate fatigue system under random loading has been established. In future work, statistical models to provide a potential tool for corrosion fatigue life prediction will be establishe. When fatigue-tested in hydrogen charging environment, the FCP rate was accelerated as compared by that tested in air, regardless of types of amplitude. The fatigue life of hydrogen charged specimens tested under random loading was longer than that of specimens tested under a constant amplitude, because of an average lower amplitude appeared in random loading.