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研究生:詹淂詳
研究生(外文):TE-HSIANG CHAN
論文名稱:冷加工與熱處理對AA7055鍛造型鋁合金微結構與機械性質的影響
論文名稱(外文):Effect of cold deformation and heat treatment on microstructure and mechanical properties of AA7055 wrought aluminum alloy
指導教授:李勝隆李勝隆引用關係
指導教授(外文):Sheng-Long Lee
學位類別:碩士
校院名稱:國立中央大學
系所名稱:機械工程學系在職專班
學門:工程學門
學類:機械工程學類
論文出版年:2020
畢業學年度:108
語文別:中文
論文頁數:56
中文關鍵詞:AA7055冷輥織構再結晶
外文關鍵詞:AA7055cold rolltexturerecrystallization
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本研究係探討固溶處理前之冷加工量(0%、5%、10%、20%、30%、50%)以及不同時效處理(T6、T76、T77)對於AA7055高強度鍛造鋁合金微結構與機械性質的影響,藉由光學顯微鏡(OM)、穿透式電子顯微鏡(TEM)、導電度量測(%IACS)、拉伸試驗以及維氏硬度計等,研究合金加工量對微結構與機械性質的影響。
結果顯示,當冷加工量越大時,產生的輥軋織狀晶就越多,並且在30%以上的冷加工量產生一組平行的剪切帶,在50%的冷加工量時,出現第二組,並且剪切帶與加工方向的角度逐漸減小。熱處理(T76)後,加工過的合金發生退火的三個階段,分別是回復、再結晶以及晶粒成長,而再結晶的程度是隨著加工量的增加而增加,而晶粒成長後的晶粒尺寸則與加工量成反比。冷輥時,硬度逐漸上升、導電度逐漸下降,固溶處理後,硬度及導電度回復至未冷加工的狀態。另外,合金經過T6時效處理後晶界上擁有細密連續的析出物,經提高時效溫度的T76與T77時效,晶界上析出物呈現粗大且不連續狀,也有無析出帶(Precipitation free zone, PFZ)的產生;由於基地與析出物之電位差,不連續狀之析出物使得T76與T77擁有較佳的抗剝落腐蝕能力。T76態因時效時間的延長也使得晶粒內之析出物粗大而降低合金之強度,T77態因重新再時效而有效地將強度回到頂時效之強度。

關鍵字: AA7055、冷輥、織構、再結晶
This study investigated the effects of cold working before solution treatment (0%, 5%, 10%, 20%, 30%, 50%) on the microstructure and mechanical properties of AA7055-T76 high strength forged aluminum alloy, and improved AA7055-T76 High-strength aluminum alloy properties, by optical microscope (OM), conductivity measurement (% IACS), tensile test and Vickers hardness tester, etc. , to study the effect of alloy processing on microstructure and mechanical properties .
The results show that when the amount of cold working is larger, the number of texture structure increase, and the cold working amount of more than 30% produces a set of parallel shear bands, and at the 50% cold working amount, the second group appears. Also, the angle of the shear band to the rolling direction is gradually reduced. After heat treatment (T76), the processed alloy undergoes three stages of annealing, namely recovery, recrystallization & growth, and the degree of recrystallization increases as the amount of processing increases. The grain size after grain growth is inversely proportional to the amount of processing. In the case of a cold roll, the hardness gradually rises and the conductivity gradually decreases. After the solution treatment, the hardness and electrical conductivity recover to the state of not being cold worked. In addition, AA7055 aluminum alloy has fine and continuous precipitates on the grain boundary after T6 aging treatment, and the aging temperature is increased by T76 and T77. Thus, the precipitates on the grain boundary are coarse and discontinuous, and the precipitate free zone(PFZ) occur; due to the potential difference between the substrate and the precipitates, the discontinuous precipitates make T76 and T77 have better resistance to exfoliation corrosion(EXCO). The elongation of the T76 state also causes the precipitates in the grains to be coarse and the strength of the alloy to be lowered. The T77 state effectively returns the
strength to the peak aging due to re-aging.

Keywords: AA7055, cold roll, texture, recrystallization
中文摘要 I
英文摘要 II
誌謝 III
總目錄 IV
圖目錄 VI
表目錄 VIII
一 .前言與文獻回顧 1
1.1鋁合金簡介 1
1.2 AA7055高強度鋁合金簡介 2
1.3 Al-Zn-Mg-Cu合金之析出強化機制 4
1.4 加工製程與微結構之關係 10
1.5輥軋製程對再結晶之影響 13
1.6冷輥軋與微結構及機械性質之關係 15
1.7實驗目的 17
二 .實驗步驟 18
2.1熱輥軋 19
2.2完全退火 20
2.3冷輥軋 20
2.4固溶處理 20
2.5時效處理 21
2.6光學顯微鏡OM 21
2.7穿透式電子顯微鏡TEM 22
2.8導電度 22
2.9硬度測試 22
2.10拉伸試驗 22
2.11剝落腐蝕試驗 23
三 .結果與討論 24
3.1微結構觀察 24
3.1.1熱輥軋之微結構觀察 24
3.1.2退火態之微結構觀察 25
3.1.3冷輥態之微結構觀察 27
3.1.4固溶水淬態之微結構觀察 29
3.1.5 T76態之微結構觀察 31
3.1.6.輥軋對微結構影響之評估 32
3.2 加工量對機械性質(硬度)之影響 34
3.3 加工量對導電度之影響 35
3.4熱處理對剝落腐蝕之影響 37
3.5熱處理對材料機械性質之影響 39
四 .結論 41
五 .參考文獻 42
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