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Please use this identifier to cite or link to this item: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/9524

Title: 高強度鈦合金腐蝕、機械性質及接合特性研究-高強度鈦合金銲件疲勞特性研究
Fatigue Crack Growth Behavior of High Strength Titanium Alloys
Authors: 蔡履文
Contributors: NTOU:Institute of Materials Engineering
國立臺灣海洋大學:材料工程研究所
Keywords: 雷射銲接;缺口拉伸試驗;疲勞裂縫成長試驗;Ti-6Al-4V;SP700
Laser welding;Notch tensile test;Fatigue crack growth;Ti-6Al-4V;SP-700
Date: 2005-08
Issue Date: 2011-06-28T07:09:26Z
Publisher: 行政院國家科學委員會
Abstract: 摘要:結構用高強度鈦合金一般均採用α-β 型, 其中代表性合金為 Ti-6Al-4V,但由於更高強度或較佳成型性需求,同類型鈦合金已逐步取代 原使用之Ti-6-4,如新發展之SP 700 或高強度Ti-6Al-6V-2Sn 等。相較於 Ti-6-4 合金,SP 700 有較佳之成型性,700℃ 熱加工時即具有超塑性,由 於其細化組織因此在相同強度等級,SP 700 比Ti-6-4 有較佳延性及疲勞強 度。另一方面Ti-6-6-2 銲道韌性則優於Ti-6-4,或具有較高延展性。 本研究為針對3 種α-β 型鈦合金,進行板材及銲件之系列機械性能測 試,試驗內容包括硬度量測、衝擊試驗、缺口拉伸及疲勞裂縫成長試驗等。 銲後銲道進行銲後熱處理,並比較銲後熱處理前後伴隨之性能變化。由於 鈦合金顯微組織將明顯影響其各種機械性質,因此將使用X-ray 繞射方式, 量測母材及銲道內各不同組織比例,同時選擇部份銲道進行微細組織TEM 觀察,評估不同顯微組織對α-β 型鈦合金機械性能之影響。溫度效應對 鈦合金性能之影響相關研究較少,因此本研究第三年度擬將針對α-β 型 鈦合金,進行上述各項不同高溫機械特性評估。
The effect of coarse welding structures, which were made by a 5 kW CO2 laser, on the notched tensile strength (NTS) and fatigue crack growth characteristics of two α+β titanium alloys (Ti-6Al-4V and SP-700 alloys) was investigated in this study. SP700 welds showed the a quick response to age-hardening as the base plate. Moreover, Ti-6-4 weld showed a sluggish reaction in aged hardness during aging over the temperature range 500 to 600o C. Aged SP-700 welds were found to be suffered from notch embrittlement especially in the peak aged condition, but not for Ti-6-4 welds. Coarser solidified structure and higher aging temperature were more likely to induce intergranular dimple fracture in SP-700 welds. All Ti-6-4 weld showed nearly same fracture features; transgranular dimple fracture with the crack growth on specific plane. Fatigue crack growth tests revealed that SP-700 alloy had a slightly higher fatigue crack growth rate (FCGR) than the Ti-6-4. The zigzag crack path in the FZ of Ti-6-4 laser welds resulted in a reduced FCGR.
Relation: NSC94-2216-E019-006
URI: http://ntour.ntou.edu.tw/ir/handle/987654321/9524
Appears in Collections:[材料工程研究所] 研究計畫

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