Ti-6Al-4V鈦合金電子束銲件之高週疲勞特性研究

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Title:	Ti-6Al-4V鈦合金電子束銲件之高週疲勞特性研究
Authors:	林緯瀚;Lin, Wei-Han
Contributors:	機械工程學系
Keywords:	電子束銲接;鈦合金;疲勞壽命;平均應力;electron beam welding;titanium alloy;fatigue life;mean stress
Date:	2017-07-27
Issue Date:	2017-10-27 16:18:08 (UTC+8)
Publisher:	國立中央大學
Abstract:	本研究以Ti-6Al-4V鈦合金為實驗材料，選擇對接接頭，進行電子束銲接(EB銲)，針對鈦合金銲件在硬度、拉伸、等負荷振幅及變動負荷振幅下之疲勞性質及疲勞壽命分析模式進行深入研究，檢視鈦合金銲件設計規範的適用性。並對Gerber與Goodman平均應力修正方法進行評估。研究結果顯示，在硬度方面，電子束銲件最高硬度位於銲道區，熱影響區次之，母材區硬度最低。在拉伸性質方面，電子束銲件平均拉伸強度為1034 MPa，銲道拉伸強度高於母材。在等振幅疲勞性質方面，對接接頭的電子束銲件疲勞強度高於AWS D1.9規範設計曲線，經由Haigh圖的觀察，可知Ti-6Al-4V銲件落在Haigh圖之Goodman與Gerber平均應力修正方程式之間。在變動振幅疲勞性質方面，不論平均應力為拉伸(傳動歷程)或是輕微壓縮(支架歷程)時，鈦合金Ti-6Al-4V電子束銲件之疲勞壽命預測皆適用Goodman平均應力修正法。 ;In this study, Ti-6Al-4V titanium alloy weldments with butt joint were produced by electron beam welding (EB welding). Several tests including microhardness, tensile, constant amplitude fatigue and variable amplitude fatigue were performed. The experimental S-N curves were compared to the fatigue design curves recommended by the International Institute of Welding, American Welding Society. Two mean stress correction methods, Goodman and Gerber, were evaluated. For electron beam welding joints, the highest microhardness occured in the fusion zone. Both the broken positions of tensile and fatigue specimens were in the base metal. Electron beam welding butt joints of Ti-6Al-4V alloy illustrated higher fatigue strength as compared to the fatigue design curves of AWS D1.9 standard. The results showed that the fatigue of electron beam welding specimens under the transmission history and bracket history could be predicted using the Goodman mean stress correction method
Appears in Collections:	[Graduate Institute of Mechanical Engineering] Electronic Thesis & Dissertation

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