6061-T6鋁合金T型惰性氣體鎢極電弧銲接件之疲勞性質研究

徐逢邑(Feng-yi Hsu)

指導教授 ： 黃俊仁

國立中央大學/工學院/機械工程學系/碩士(2014年)

摘要

本研究實驗材料為熱處理型6061-T6鋁合金，以惰氣鎢極電弧銲接(TIG銲)進行T字型銲接，探討鋁合金T字型銲接結構件於等負荷振幅下之疲勞性質並與各銲接規範比較。
研究結果顯示T字型銲件疲勞試片斷裂點全位於熱影響區靠近銲道上的位置。T字型銲件在較高壽命區間(N = 10^5 ~ 10^7)其疲勞強度(S - N曲線)皆比 IIW、BS8118 及 Eurocode 9 等規範之對應的設計曲線高，三種規範之設計較為保守。在較低壽命區間(N = 10^4 ~ 10^5)，以 IIW 規範與實驗值差異最小。而在變動負荷振幅下之疲勞性質，並研究其疲勞壽命分析模式方面，綜合拉張平均應力歷程(TRN歷程)及輕微壓縮平均應力歷程(BRK歷程)變動振幅疲勞測試結果，建議以Goodman平均應力法進行修正，可得較佳的疲勞壽命預測。

關鍵字

6061-T6 ； 鋁合金 ； 氣體鎢極電弧銲 ； 疲勞壽命

並列摘要

In this study, 6061-T6 aluminum alloy was welded in T joint by inert gas tungsten arc welding (TIG welding). The fatigue properties of the welded joints under constant and variable amplitude loading were obtained and compared with international standard of welding.
The results showed the fracture of the 6061-T6 T joint were observed at the Heat-Affected Zone (HAZ), where showed the lowest microhardness of fatigue test specimens. The fatigue strength of welded joints are higher than the fatigue design curves, which provided from three international welding standard, IIW, Eurocode 9 and BS 8118, respectively. In the short life region, we can find the experiment of fatigue strength data are more conforming to the fatigue design curve of IIW than the other two standards. Overall, the fatigue strength data of the three standard of welding are more conservative than the experiment of results.
Under variable amplitude loading, effect of mean stress should be taken into consideration when the fatigue life of welded joints predicted. The Goodman modification was more consistent with the experiment results than Gerber modification.

參考文獻

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