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|Title: ||T-200 麻時效鋼缺口拉伸性質及氫脆影響研究|
The effect of microstructures and hydrogen permeation on the notch tensile properties of T-200 maraging steel
|Authors: ||Huei-Lin Lu|
|Contributors: ||NTOU:Institute of Materials Engineering|
maraging steel;Sulfide stress corrosion cracking;Hydrogen permeation;Hydrogen embrittlement
|Issue Date: ||2011-06-30T07:23:16Z
|Abstract: ||本研究針對 T-200 麻時效鋼，於大氣、氣態氫環境及飽和硫化氫水溶液中，進行缺口拉伸強度比較及破裂特徵觀察。並利用電化學氫滲透法測量不同條件試件之穿透滲透速率(Db)、有效擴散速率(DL)、氫擴散速率、視固溶度(Capp)，進而評估不同試件處理條件其氫脆之敏感性。經過482 ℃/4hr 時效處理後試件，比起固溶試件皆有視固溶度(Capp)上升，但有效擴散係數(DL)下降之趨勢。晶粒大小對於T-200之氫擴散性質影響並不大，氫穿透擴散係數(Db)則會因晶界析出物阻擋，而有到顯著的改變，也就是說於時效試件中觀察到穿透擴散係數(Db)低於有效擴散係數(DL)。在氫氣中，時效試件中特別是粗晶組織比起細晶組織有更高的氫脆敏感性。相較之下，較低強度之固溶試件於氣態氫環境中抗氫脆性較佳，但於飽和硫化氫水溶液所有試件均呈現高氫脆性。|
Notched tensile tests were performed under a slow displacement rate to evaluate the influence of aging treatment and hydrogen-charging on the notched tensile strength (NTS) and fracture characteristics of T-200 maraging steel. Hydrogen breakthrough diffusivity (Db), effective diffusivity (DL), permeation flux and apparent solubility (Capp) of the specimens were determined by an electrochemical permeation method. The results indicated that the specimens aged at 482℃/for 4 h obviously raised the Capp with a decreased DL as compared to those of the solution-treated ones. In general, the grain size of T-200 specimens did not play a significant role in the hydrogen permeability experiment. The magnitude of Db decreased considerably in the aged specimens due to the presence fine precipitates and reverted austenite at grain boundaries, resulting in a lower Db than DL. An aged specimen with a coarse-grained structure was more sensitive to hydrogen embrittlement than the fine-grained one, even though they had the same strength in air. In contrast, the solution-treated specimen with a lower strength was resistant to gaseous hydrogen embrittlement but susceptible to sulfide stress corrosion cracking. The fracture appearance of the specimens tested in hydrogen-containing environments could also be related to the way of hydrogen transport to the plastic zone ahead of notch tip.
|Appears in Collections:||[材料工程研究所] 博碩士論文|
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