本研究探討陰極保護對S355低碳鋼及其焊件氫損傷之影響。藉由S355經過焊接後，於0.1 M 硫酸水溶液中進行陰極定電位充氫試驗，利用彈簧拉伸試驗測其機械性質變化，並透過SEM觀察其破斷面，進而比較S355及焊道對氫損傷之敏感性，再藉由S355經熱處理後，以EBSD分析其內部結構，藉此來分析並推斷其造成氫損傷之可能機制。
實驗將兩塊 S355 ML 低合金鋼鋼板經潛弧銲接後形成一大塊狀銲件。銲接採雙 V 槽使用兩種銲條分兩道進行，先以第一種銲料進行打底，S355低合金鋼便於後續以第二種銲料進行多道次銲接，第一種銲料型號為 Bohler HL53T-MC，第二種銲料型號為 Bohler Ti60 T-FD 。經過焊接後之試體，分別於母材S355及焊接部分取材進行充氫試驗，未經充氫下，焊道之最大拉伸強度為694MPa，S355為491MPa，經過越長的充氫時間，兩者的機械性質皆會隨之下降，但焊道的部分直到經過48小時的充氫，都還具有一定的延性及拉伸強度，其破斷面也並未顯現明顯劈裂跡象，因此焊道對氫損傷敏感性較S355來的低。
基於此結果，為了改善S355的氫損傷敏感性，將S355分別進行應力消除退火及均質化熱處理，於EBSD分析下，可以得知兩者內部之缺陷，如差排，經過熱處理後確實減少，而充氫試驗結果表明，兩者機械性質較原始S355也有部分改善，且均質化熱處理之S355，在經過48小時的充氫後，並未顯現任何明顯受到氫損傷而產生劈裂的跡象。

This study investigated the effect of cathodic protection on hydrogen damage of S355 steel and its weld. Accelerated hydrogen charging was performed in 0.1 M H2SO4 solution under cathodic polarization. The change of mechanical properties with different hydrogen charging condition were evaluated by conducting spring-loading tensile test. The fracture surface of each specimen after tensile test was observed by SEM to compare the sensitivity of hydrogen damage. To determine the possible mechanism of hydrogen damage we did heat treatment for S355. And the internal structure of the S355 was analyzed by EBSD after heat treatment. The maximum tensile strength of the weld bead without hydrogen charging is 694MPa and 491MPa for S355. The longer the hydrogen charging time, the lower the mechanical properties of both. However, the part of the weld bead still has a certain ductility and tensile strength until after 48 hours of hydrogen charging, and the fracture surface does not show obvious signs of cleavage. For S355 after annealed and homogenized, the defect and dislocation density is decreased, from the result of KAM, the KAM peak value of S355 – as received is about 3.5, but after heat treatment, the peak value will get lower to 2 or less than 1 degree. So hydrogen content will decrease with the same hydrogen charging time. From these result, the induced factor of hydrogen damage is caused by rolling, it would cause more defect or dislocation in the microstructure to trap the hydrogen.

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