臺灣博碩士論文加值系統

本研究選用材料為厚度1mm之AA6022-T4E29鋁合金薄板，第一部份針對母材試件與其經Nd:YAG雷射走銲之試件，分別施予0%、3%、6% 及0%、3%之預應變，再以模擬汽車板金之塗裝烘烤程序(Paint Bake Cycling, PBC)或175℃/1000min條件進行熱處理。以穿透式電子顯微鏡(TEM)分析不同預應變與熱處理程序後之析出相與顯微結構的變化，並探討這些變化對母材與銲件之機械性質的影響。第二部份對母材施予T4E29+預應變+預時效+PBC、重新固溶+T4(8days)+預應變+預時效+PBC、T4E29+預時效+預應變+PBC 三種不同處理程序，其中預應變為0%、3%、6%，預時效溫度為175℃，時間分別為100 min、300 min、500 min、1000 min，探討預應變與預時效之影響與最佳之預時效時間。
第一部分之結果顯示，在母材試件：隨預應變(差排密度)的增加，母材(T4E29)與其經PBC處理試件之降伏強度與硬度即隨之提升，抗拉強度並沒有明顯改變，此外，經PBC處理後之試件，抗拉、降伏強度與硬度皆有少許的提升；而母材經175℃/1000min處理試件因有β"之強化相析出，使得降伏強度與硬度較上兩組試件為高，但隨預應變量的增加，由於β"相粗大化並有過時效之Q'相產生而使硬度與強度下降。在銲接試件：未經熱處理與經PBC處理試件因隨預應變的增加，差排亦隨之的增生，故降伏強度與硬度隨預應變量增加而升高；經175℃/1000min處理試件則因β"相的析出，而使其強度較前兩組試件為高，且亦隨預應變量的增加而升高。第二部份結果顯示，整體之抗拉與降伏強度以T4E29+預時效+預應變+PBC試件最高，T4E29+預應變+預時效+PBC則次之，重新固溶+T4(8days) +預應變+預時效+PBC之試件最低。T4E29+預時效+預應變+PBC之試件，在預時效1000min時具有最高之平均抗拉與降伏強度；T4E29+預應變+預時效+PBC與重新固溶+ T4(8days)+預應變+預時效+PBC試件之平均最高抗拉強度，分別是在預時效0 min與300 min，而平均降伏強度則皆在預時效500min處。

This study includes two parts. In part one, AA6022-T4E29 aluminum alloy sheet parent metal of 0%, 3%, and 6% pre-strain together with Nd : YAG laser welded AA6022-T4E29 weldment of 0% and 3% pre-strain were heat treated to simulate the Paint Bake Cycling (PBC) or 175℃/1000 min. Transmission electron microscope was utilized to analyze the characteristics of precipitates and microstructure after pre-strain and heat treatment. Subsequently, the effects of precipitates and microstructure variation on the mechanical properties of parent metal and weldment were discussed. In part two, the parent metal is proceeded one of three kinds of treated processes which are T4E29 + pre-strain + pre-aging + PBC (TPSPAP), solution treated (at 560℃/20min) + T4(8days) + pre-strain + pre-aging + PBC (STPSPAP), and T4E29 + pre-aging + pre-strain +PBC (TPAPSP) to investigate the difference between mechanism properties and the best aging treated time. The level of the pre-strain and pre-aging time are 0%, 3%, 6% and 100min, 300min, 500min, 1000min, respectively.
The results of part one, the yield strength of the parent metal both with the PBC process and without the heat treatment will increase with the increasing pre-strain accordingly. After the heat treatment with 175℃/ 1000 min, because of the β" phase precipitated in the matrix, it makes both the yield strength and the hardness are higher than the specimen both with and without the PBC. While the pre-strain increases continuously, the β" phase transformed into coarser and over aged Q' phase to reduce hardness and strength. In the weldment, because of the dislocation increased in the weld metal, both with the PBC process and without the heat treatment, the yield strength increases as pre-strain increases. After the PBC process, because of the precipitation produced, the tensile strength and the yield strength are higher than the weldment without the heat treatment. Further, the strength of weldment with the PBC process is higher than the strength of weldment without the heat treatment. However, because after the heat treatment with 175℃/1000 min, the β" phase were produced, the strength is higher than the former two series of specimens and increases with increasing pre-strain. Part two’s results indicate the specimens treated under TPAPSP process have the highest tensile strength or the yield strength, while that treated under STPSPAP process have the lowest. The highest of the tensile strength in TPAPSP specimens is at the pre-aging 1000 min, while that in the processing of TPSPAP and STPSPAP are separately at pre-aging 0 min and 300min, and the yield strength of both series specimens are at the pre-aging 500min.

摘要 I
英文摘要 II
總目錄 V
表目錄 VII
圖目錄 VIII
第一章 前言 1
第二章 文獻回顧 3
第三章 理論基礎 7
3-1 雷射基礎 7
3-1-1 基本介紹. 7
3-1-2 雷射銲接原理 8
3-1-3 雷射參數之影響 9
3-2 Al-Mg-Si 合金之析出機制 13
3-2-1 AA6022析出程序與析出物之種類. 13
3-2-2 DSC與TEM對析出物之分析 14
3-2-3 時效後之析出對機械性質之影響 16
3-2-4 自然時效、預時效、人工時效對機械性質的影響 17
3-2-5 預應變對析出之影響 19
第四章 實驗規劃與流程 22
4-1實驗規劃 22
4-2實驗流程 22
4-2-1材料前置處理與銲接試驗 22
4-2-2熱處理試驗 25
4-2-3機械性質試驗 25
4-2-4TEM顯微金相試驗 26
4-3實驗之儀器設備 27
第五章 結果與討論 32
5-1拉伸與硬度試驗 32
5-1-1 母材試件 32
5-1-2 銲接試件 33
5-2 斷口形貌分析 34
5-3 顯微結構 35
5-3-1 母材試件 35
5-3-2 銲接試件 37
5-4素材之預應變與預時效程序對機械性質之影響 39
5-4-1預時效與預應變程序變化 39
5-4-2綜合結果 42
第六章 結論 43
第七章 參考文獻 80

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