本研究以Ti-6Al-4V鈦合金為實驗材料，採用自體銲接方式進行電子束銲接(EBW)，檢視鈦合金銲件之銲道與母材在等負荷振幅及變動負荷振幅負載下之疲勞裂縫成長性質，利用破壞力學評估在變動負荷振幅負載下之疲勞壽命。再研究不同應力比下對於銲件疲勞裂縫成長的影響，最後探討此材料銲道與母材的破壞韌性。 研究結果顯示，銲道抵抗疲勞裂縫成長能力較母材佳，且在疲勞裂縫成長實驗中，可觀察到銲道在受到不同應力比時，其產生的影響較小。若在相同的變動振幅負載條件下，銲道壽命為母材的4倍。母材的破壞韌性JIC為66 N-mm/mm2，銲道為30 N-mm/mm2。綜觀本實驗所使用之各種修正模式下，靜態破壞修正模式對於預測疲勞裂縫成長壽命最為準確。 ;In this study, we chose Ti-6Al-4V titanium alloy processed by the implemented Electron Beam Welding (EBW) for the experiment. The objectives were as follows. (1) To obtain the materials properties such as fatigue crack growth rate and fracture toughness. (2) To understand the effects of stress ratio on the fatigue crack growth rate. (3) To establish the optimum method for predicting fatigue life of a cracked specimen. The results showed that the anti-crack growth ability of weld bead was better than the base material. The fatigue crack growth rate of welding bead was less affected by the stress ratio. Under the same variable amplitude loading, the fatigue life of weld bead was about four times of base material. Fracture toughness JIC of base material and welding bead was 66 N-mm/mm2 and 30 N-mm/mm2, respectively. With respect to fatigue crack growth life prediction, the static fracture correction model was the most accurate one.
