| 摘要: | 5000 系鋁鎂合金為鍛造型非熱處理鋁合金，具有良好的耐腐蝕性與焊接 性，已被廣泛應用於3C 機殼、船艦結構、車輛骨架、儲存槽等用材，但鎂含量 高於3wt%之鋁鎂合金若長時間暴露於高溫(50~200 )環境下， (Mg2Al3)相會沿 著晶界、差排等高能量處析出，在腐蝕環境中，與鋁基地之間形成電位差，造成 伽凡尼腐蝕現象，若β 相(Mg2Al3)在晶界上連續分佈，將使原本具耐蝕性之鋁鎂 合金發生敏化，長時間使用下將對生命財產安全造成嚴重危害，但微結構變化及 敏化程度(Degree of Sensitization, DoS)均無法從外表目視觀測，須藉由拉伸試 驗、硬度試驗、金相組織觀察、ASTM G67 NAMLT 硝酸重量損失試驗等破壞性 檢測方可得知其變化。 但對結構用材而言，並無法藉由破壞性檢測來進行相關試驗。因此，利用 非破壞性檢測(Non-Destructive Testing, NDT)技術，如渦電流(Eddy Current)量測或 超音波(Ultrasonic)檢測等，在不破壞材料情況下，檢測材料內部微結構、缺陷及 析出物等狀態是極為需要與有價值之研究。 另外，含微量鋯的AA5383 鋁鎂錳合金為常用的AA5083 之改良型合金，具 有較高之機械性質（強度及延性）與熱穩定性，國內現正用於軍艦之結構用材上， 未來使用量預期會更大，其長時間使用後之敏化現象，仍有待了解與克服。 由於鋁鎂合金敏化肇因於相之析出程度，與鋁鎂合金本身之鎂含量有密切 關係，申請人發現藉由渦電流量測及超音波檢測，能夠量測鋁鎂合金在不同鎂固 溶量(3-6wt%)下之導電度與聲波速度，申請人對於這些初步研究結果覺得有深入 探討之價值。且就所蒐集之文獻發現，AA5383 鋁鎂錳合金相關研究著重於鋯元 素對於鋁鎂合金之機械性質與超塑成型性之探討；並無涉及腐蝕性質研究。 基於國內5000 系合金使用資訊的建立，所以規畫此三年期之研究計畫，每 一年度之研究規畫如下: 第一年: 鎂含量(3~6%wt)與安定化對5000 系鋁鎂合金之腐蝕與機械性質之影響 第二年: 非破壞性檢測5000 系鋁鎂合金之腐蝕與機械性質 第三年: 鋯與安定化對AA5383(Al-4.7Mg-0.7Mn)合金腐蝕與機械性質之影響 期待藉由本研究，深入探討上述改善之學理機制，並成功探討鎂含量(3-6wt%) 之鋁鎂合金導電度及聲波速度與腐蝕程度、合金強度之關係，期望透過非破壞性 檢測能夠準確評估合金因敏化導致的耐蝕性及機械性質下降之程度。 ;5000 series forging alloys have been widely applied to the marine, auto and storage tanks applications. These alloys precipitates β-(Mg2Al3) phase in corrosive environments in 65-200℃. Due to the potential difference between Al-matrix and β phase, resulting in a Galvanic corrosion. The alloy subject to severe corrosion damage, if the β phase is a continuous distribution on the grain boundaries, which called sensitization. In order to detect the degree of the sensitization, mechanical test, corrosion test and microstructure observation should be applied. However, such these testing belongs to destructive testing, which is unable to apply on the structure materials. Therefore, Non-Destructive Testing such as Eddy Current testing or Ultrasonic testing detect the state of microstructure, defects and precipitations are a valuable research. Because the precipitation of the β phase leads to the sensitization of 5000 alloys, the β precipitation amount depends on Mg contents. This research will be conducted to discuss the relationship between IACS, sound velocity and properties of the alloys under the Mg contents 3-6wt%.Hope this study will be helpful for the accuracy of using Non-Destructive Testing on evaluating the properties of 5XXX alloys. In addition, containing trace zirconium AA5383 Al-Mg alloy for the commonly used AA5083 modified alloy. It has higher mechanical properties and thermal stability, our country is now being used for warships structural, the future use of is expected to be greater, after its long-term use of sensitization, remains to be understood and overcome. Based on the establishment of the information on the use of the 5000 series alloy, a three-year study is planned. The research plan for each year is as follows: First year: Effect of Mg content (3 ~ 6% wt) and stabilization on corrosion and mechanical properties of 5000 series Al-Mg alloys. Second year: Non-destructive testing of the corrosion resistance and mechanical properties of 5000 Series Al-Mg alloys. Third year: Effect of Zr and stabilization on corrosion and mechanical properties of the AA5383 alloy. It is expected that the relationship between the conductivity and the sound velocity of the Al-Mg alloy, the corrosion intensity and the strength of the alloy will be explored. Hope the research results are helpful, as an important reference, for the users and manufacturers. |
