Low Cycle Fatigue Behavior of Ti-Alloy

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Project title

Code/計畫編號

NSC89-2216-E019-010

Translated Name/計畫中文名

高性能材料之銲接與修補製程最佳化研究---子計畫三：鈦合金銲接構件之彎曲低週疲勞

Project Coordinator/計畫主持人

Shing-Hoa Wang

Funding Organization/主管機關

National Science and Technology Council

Department/Unit

Department of Mechanical and Mechatronic Engineering

Website

https://www.grb.gov.tw/search/planDetail?id=584766

Year

2000

Start date/計畫起

01-08-2000

Expected Completion/計畫迄

01-07-2001

Bugetid/研究經費

714千元

ResearchField/研究領域

材料科技

本實驗研究目在探討三種不同微觀組織的鈦合金，於應用不同應變速率及應變振幅的情況下，其原素材及氣護鎢極電弧銲銲件對低週疲勞性質的比較，實驗結果顯示增加應變速率均會使 Ti-64 、CP-Ti 和 Ti-153 的拉伸抗拉強度和降伏強度上升，且其伸長量會下降。在疲勞試驗方面，應變速率升高會使疲勞強度上升，高應變振幅呈循環應力軟化，低應變振幅則為循環應力硬化，且 Ti-153 對應變速率的敏感性較 Ti-64 高，Ti-64 銲件裂縫出現於母材區，其疲勞強度劣於原素材，Ti-153 銲件裂縫位於銲道處，且其銲件疲勞強度優於e& =5 ×10-3 s-1時的素材疲勞強度，但劣於e& =1×10-2 s -1 時素材疲勞的強度。Ti-64 銲道溶融區主要形成的組織為針刺狀麻田散鐵a¢，溶融區的維氐硬度值最高。純鈦銲件之耐疲勞強度比原材優越，基於銲道之補強作用。Three different titanium alloys (pure Ti, Ti 64 and Ti153) with different microstructures and their welds were used to study the effect of strain rate and strain amplitude on the properties of low cycle fatigue. It shows that the ultimate tensile strength and the yield strength increase with increasing strain rate but the elongation decreases. Similarly, fatigue strength increases with strain rate. Alloys undergo cyclic strain hardening at the relative small strain amplitude. On the other hand, alloys undergo cyclic strain softening so that stress range decreases with increasing number of strain cycles. The ductile pure Ti and Ti 153 alloy exhibit more sensitive to strain range change than high strength Ti 64. The fatigue strength of Ti 64 welds is inferior to that of parent metal and the failure occurs at the base metal zone. However the fatigue failure of Ti 153 happens at the weld.

Keyword(s)

鈦合金
低週疲勞
應變速率
銲接
Titanium Alloys
Strain Rate
Weld
Low Cycle Fatigue

DSpace CRIS

Low Cycle Fatigue Behavior of Ti-Alloy

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