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Please use this identifier to cite or link to this item: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/42703

Title: 304L不鏽鋼板材及308L不鏽鋼銲道之鹽霧應力腐蝕研究
The Stress corrosion cracking of 304L and 308L stainless steel weld metal in salt-spray environment
Authors: Hsu, Chia-Hao
許家豪
Contributors: NTOU:Institute of Materials Engineering
國立臺灣海洋大學:材料工程研究所
Keywords: 鹽霧;應力腐蝕;不鏽鋼銲件;滾軋;敏化處理;極化掃描
salt spray;stress corrosion cracking;welding;cold-rolled;sensitization treatment;electrochemical polarization tests
Date: 2015
Issue Date: 2017-05-24T08:17:27Z
Abstract: 本研究為將304L板材及308L銲道先經滾軋處理後進行敏化,模擬銲道的敏化現象。後續將試片置入於80℃-5wt%之加熱鹽霧環境之中,觀察不同試件之應力腐蝕龜裂之劣化機制及重量損失試驗,探討304L不銹鋼及308L銲道試件組織對其應力腐蝕破裂之影響。實驗結果顯示,U型彎曲試件及重量損失試片在鹽霧環境中進行288hr測試,滾軋試件裂縫起始主要呈現穿晶破裂特徵,易從交叉滑移帶產生侵蝕並生成裂縫。經過滾軋敏化試件表面晶界嚴重弱化,表面產生大量的沿晶應力腐蝕。308L原始銲道滾軋試件侵蝕主要發生在凝固組織周圍及周圍產生的滑移帶上,再沿著骨骼狀凝固組織破裂。經過滾軋敏化試片,表面滑移帶雖大量減少,但破裂模式仍是沿著凝固組織破裂。重量損失試驗中也觀察到304L滾軋試片主要沿著滑移帶產生蝕孔且表面蝕孔較為完整。經過滾軋敏化後試片,則在蝕孔周圍觀察到微裂縫的產生。308L銲道滾軋試片及滾軋敏化試片仍是沿著骨骼狀凝固組織周圍產生侵蝕,且重量損失和彎曲試驗相比,發現重量損失越嚴重表面的破裂程度也隨之升高。透過電化學循環動態極化試驗,發現結果與重量損失較為相似,304L滾軋試件蝕孔皆出現在滑移帶交界處,而滾軋敏化試片蝕孔周圍產生微小裂縫產生,308L滾軋及滾軋敏化仍是沿著滑移帶周圍進行侵蝕,從腐蝕電流與重量損失相比,滾軋敏化後試片腐蝕電流及重量損失皆相對較大。最後將三個實驗結合推測出,在有應力的環境下,蝕孔優先產生在差錯滑移帶上再沿著蝕孔之間延伸產生嚴重的應力腐蝕。
In this research, ER 308L was utilized as the filler metals for the welds of a 304L stainless steel(SS) substrate, which was prepared via a tungsten arc-welding process in multiple passes. The part of sample are cold-rolled (20% thickness reduction) and others been sensitization treatment (650℃/10 h). the sample of U-bend and weight loss tests were conducted by testing the SS substrate and welds in a salt spray contain ing 5wt% NaCl at 80℃ to evaluate their stress corrosion cracking (SCC) susceptib ility. The weight loss test results indicate that CW and CWS are worst in a salt spray environment and the corrosion is focus on the surface of slip plane. the SS just pitting corrosion on surface. The U-bend test indicate cold-rolling and sensitization treatment will promote the fracture of sensitivity. On the other hand, the dissolution of 308 deposits is focus on skeletal structure. Eventually, no matter weight-loss test or electrochemical polarization tests, the worst of sample is sensitization treatment.
URI: http://ethesys.lib.ntou.edu.tw/cgi-bin/gs32/gsweb.cgi?o=dstdcdr&s=G0010255004.id
http://ntour.ntou.edu.tw:8080/ir/handle/987654321/42703
Appears in Collections:[Institute of Materials Engineering] Dissertations and Theses

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