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研究生： 黃展鴻
Wong, Chin-hong
論文名稱： 摩擦攪拌7075鋁合金組織特性及拉伸性質之後熱處理效應探討
Effects of Post-Heat Treatment on Microstructure and Tensile Properties of Friction Stir Processed 7075 Aluminum Alloy
指導教授： 陳立輝
Chen, Li-Hui
呂傳盛
Lui, Truan-Sheng
學位類別： 碩士
Master
系所名稱： 工學院 - 材料科學及工程學系
Department of Materials Science and Engineering
論文出版年： 2007
畢業學年度： 95
語文別： 中文
論文頁數： 62
中文關鍵詞： 摩擦攪拌製程 、熱處理 、7075鋁合金 、拉伸性質
外文關鍵詞： fsp, 7075 Al Alloy, tensile properties, post-heat treatment
相關次數： 點閱：100  下載：3 
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    • 7075鋁合金為高強度的熱處理型鋁合金，具有高比強度與優良的耐蝕能力，目前已廣泛應用在航空工業上。摩擦攪拌銲接（FSW）為固態接合技術，由於過程中溫度未達熔點，故無氣孔、凝固裂紋等傳統熔融銲接產生之缺陷，所以特別適合鋁合金銲接之應用。然而，在摩擦攪拌過程中對7075鋁合金有部分固溶的效果，對於其後續熱處理的影響並沒有太多的討論。針對攪拌後熱處理的影響，本研究利用與FSW原理相同的摩擦攪拌製程（FSP）施予7075鋁合金，接著處以自然時效、復原處理及人工時效處理，探討後熱處理對攪拌區（stir zone）微觀組織及拉伸性質的影響。
    實驗結果顯示，自然時效處理後延性有大幅的下降。在摩擦攪拌後對攪拌區重新施加固溶處理，發現經過自然時效後的拉伸性質有很大的改變，不但延性沒有下降而且拉伸強度也有大幅的提升。從電子微探儀（EPMA）對固溶前後的元素分佈結果顯示，攪拌後析出物濃度有分佈不均勻的現象，而經過重新固溶後會有減緩析出物濃度不均的效果，所以拉伸性質有以提升。
    攪拌區在經過自然時效後施加復原處理，會發生性質回復－即強度下降而提高延性的現象。沒有重新固溶處理的攪拌區其延性上升幅度比有重新固溶處理的為大，效果較顯著。
    摩擦攪拌後對攪拌區直接處以120℃、220℃及320℃的人工時效，發現晶粒並沒有成長的現象發生，織構上也沒有明顯差異。拉伸性質方面，拉伸強度會隨溫度的上升而下降；延性方面，120℃和220℃時延性下降，而320℃時則有所提升。

    Heat treatable Aluminum alloy 7075 has high specific strength and good anti-corrosion, which applied generally in aerospace industry. Friction Stir Welding (FSW) is a technology of solid-state joining, because the temperature of welding process had not reach the melting point, there were not stay porosity and shrinkage crack inside material. However, in FSW process will occurred solid solution phenomenon happen, but doesn’t too much researches for post-heat treatment. In this study used of FSP (which is a technique based on the principle of FSW) on aluminum alloy 7075-T6 aims at the effect of post-heat treatments: natural aging, reversion and artificial aging, discuss the variation of the microstructure and tensile properties on stir zone.
    The results of tensile test show the reduction in ultimate strength and ductility of stir zone after natural aging at 40℃/96 hours. The stir zone after solid solution treatment and natural aging would get great promotion in ultimate strength and ductility. The distribution of the precipitates concentration after FSP is unsymmetrical which observed by EPMA. It affects the tensile properties after FSP. This effect has reduced by solid solution treatment before natural aging.
    The reversion treatment recover the ductility which had a reduction by long tern natural aging, but at the expense of tensile strength. The ductility of stir zone after natural aging and reversion without solid solution treatment was higher than that zone after solution treatment.
    The stir zone samples after FSP were aged at 120℃/24hours, 220℃/1hours and 320℃/1hours after FSP. According to microstructure there were no variation on gain size and texture. The results of tensile strength would decrease while the temperature increased. The ductility after aging at 120℃and 220℃ would be decreased but increased at 320℃.

    總目錄 中文摘要…………………………………………………….………………Ⅰ 英文摘要….……………………..……..…………….……………………Ⅱ 總目錄….……………………..……..……………….……………………Ⅳ 表目錄……….………………………….………………...……..…………Ⅵ 圖目錄….………………………………...……………...…………………Ⅶ 第一章 前言………………………………………………………………...1 第二章 文獻回顧…………………………………………………………...2 2-1 熱處理型鋁合金介紹……………………...……………………...2 2-2 Al-Zn-Mg-Cu（7075）鋁合金……………………………………2 2-3 摩擦攪拌銲接/摩擦攪拌製程……..……………………………...3 2-4 攪拌後組織特性…………………………………………………..4 2-5 7000系鋁合金摩擦攪拌相關研究與傳統銲接技術比較……….5 2-6 復原處理（reversion）機理……………………………………...5 第三章 實驗步驟與方法………………………………………………….12 3-1 實驗用材料….......……………………………………………….12 3-2 摩擦攪拌製程……………..……………………………………..12 3-3 攪拌後熱處理條件………………………………………………12 3-3-1 自然時效處理……………………………………………...12 3-3-2 復原處理（Reversion）……………………………………13 3-3-3 人工時效處理……………………………………………...13 3-4 拉伸性質實驗……………………………………………………13 3-5 組織特性觀察……………………………………………………14 3-5-1 微硬度實驗………………………………………………...14 3-5-2 微觀組織觀察……………………………………………...14 3-5-3 穿透式電子顯微鏡觀察（TEM）…………………………14 3-5-4 X-ray 繞射分析…………………………………………....14 第四章 實驗結果………………………………………………………….25 4-1 微觀組織與機械性質之摩擦攪拌效應………....………………25 4-1-1 摩擦攪拌製程PD面微觀組織觀察…….………………...25 4-1-2 微硬度及拉伸性質………………………………………...25 4-2 摩擦攪拌之後熱處理效應………………………………..……..26 4-2-1 摩擦攪拌後之自然時效效應……………………………...26 4-2-2 摩擦攪拌後之復元處理效應……………....……………...26 4-2-3 摩擦攪拌後之人工時效效應……………………………...27 第五章 討論.................................................................................................49 5-1 攪拌後固溶處理對自然時效的影響探討……...……………….49 5-2 回復處理之摩擦攪拌效應之探討………………………………50 5-2-1 溫度對回復處理的影響…………………………………...50 5-2-2 摩擦攪拌效應對回復處理的影響………………………...50 5-3 攪拌後人工時效效應探討….……………………………...……51 5-3-1 拉伸破斷面觀察…………………………………………...51 5-3-2 微觀組織觀察……………………………………………...52 第六章 結論……………………………………………………………….58 參考資料…………………………………………………………………….59 表目錄 表 2-1 時效硬化處理之符號及其意義..…………………………………7 表 3-1 7075-T6化學組成（wt.%）…………..……………….………...16 表 3-2 Keller腐蝕液配置方法……………...…………………………..16 表 3-3 各種不同熱處理之代號…………………………………………17 表 4-1 BM攪拌前後之拉伸數據…………………………………….…29 圖目錄 圖 2-1 FSW示意圖………….,……….…………………………………..8 圖 2-2 7075鋁合金T6材摩擦攪拌後室溫下之自然時效曲線…….…..9 圖 2-3 Al-Zn-Mg-Cu 四元460℃ 等溫平衡相圖…………...…...…….10 圖 2-4 退化處理中硬度對退化時間示意圖………………...….………11 圖 3-1 實驗架構……………………………..…………………………..19 圖 3-2 BM（7075-T6材）試片取向及尺寸示意圖…………...………20 圖 3-3 摩擦攪拌及攪拌棒示意圖………………………………………21 圖 3-4 復元處理的處理程序…………...…………...…………………..22 圖 3-5 利用FIB切割之TEM試片……..…………….………………..23 圖 3-6 裂縫量測示意圖.........………….………….….…............……....24 圖 3-7 X-ray 試片取樣示意圖………………...………….……....…….25 圖 4-1 BM （7075-T6材）光學顯微組織圖……………………...…….32 圖 4-2 BM-F：（a）PD面微觀組織OM全圖；（b）分區示意圖….…33 圖 4-3 TMAZ微觀組織（OM）：（a）AS；（b）RS…….……….…….34 圖 4-4 SZ區微觀組織（OM）：（a）上層；（b）下層………….…..…35 圖 4-5 摩擦攪拌後PD面之硬度分佈…………………………………..36 圖 4-6 巨觀拉伸破斷面觀察：（a）BM；（b）BM-F…………...……..37 圖 4-7 40℃×96hr自然時效（包括固溶後之BM）的微硬度變化圖...38 圖 4-8 40℃×96hr自然時效後的拉伸性質：（a）UTS，YS；（b）TE， UE………………………………………………………………..39 圖 4-9 200℃油浴至120秒的微硬度變化圖...........................................40 圖 4-10 回復處理後的拉伸性質：（a）UTS，YS；（b）TE，UE …….41 圖 4-11 熱處理後之微觀組織觀察：（a）BM-F；（b）120℃×24hr； （c）220℃×1hr；（d）320℃×1hr…………………………...…..42 圖 4-12 TEM觀察的結果 （a）120h24晶界析出物型態與EDS 成分分析………….…….43 （b）120h24晶粒內析出物型態與EDS 成分分析…………….43 （c）320h1晶界析出物型態與EDS 成分分析…………….…...44 （d）320h1晶粒內析出物型態與EDS 成分分析……………...44 圖 4-13 TEM晶界觀察：（a）120h24；（b）320h1.…………....……...44 圖 4-14 熱處理後PD面之硬度分佈……………………..…….……..….45 圖 4-15 熱處理後拉伸性質：（a）UTS，YS；（b）TE，UE…….….....46 圖 4-16 熱處理後巨觀拉伸破斷面觀察：（a）120h24；（b）220h1； （c）320h1……………………………………………………..….47 圖 5-1 攪拌後ND面EMPA元素分析……………………....……...….60 圖 5-2 攪拌及固溶處理後ND面EMPA元素分析……....……..….…..61 圖 5-3 攪拌材及人工時效後拉伸破斷面觀察：（a）BM-F；（b）120h24； （c）320h1……………………………………………….….....….47 圖 5-4 攪拌材及人工時效後ND面的X-ray繞射圖形： （a）BM-F；（b）120h24；（c）220h1；（d）320h1……...……62 圖 5-5 攪拌材及人工時效後PD面的X-ray繞射圖形： （a）BM-F；（b）120h24；（c）220h1；（d）320h1…….....…..62

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