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Please use this identifier to cite or link to this item: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/13912

Title: 活性助銲劑對銲道穿深與顯微相變態之研究
The effect of activating flux on weld penetration and microstructure for structural materials
Authors: 許秉緯
Contributors: NTOU:Department of Mechanical and Mechatronic Engineering
國立臺灣海洋大學:機械與機電工程學系
Keywords: 惰性氣體遮蔽鎢極電弧銲、活性助銲劑、麻田散鐵α'、含鈦高強度低碳鋼、惰性氣體鎢極電弧銲、差排密度、雙晶麻田散鐵
A-TIG, Ti-6Al-4V, grain refinement, martensitic α´、Ti-bearing HSLA steel, TIG welding, dislocation, twin martensite
Date: 2010
Issue Date: 2011-06-30T07:30:08Z
Abstract: 本研究使用奈米尺寸顆粒的活性助銲劑於惰性遮蔽氣體電弧銲接,探討活性助銲劑對鈦合金的熔貫穿深、微觀相變態和機械性質的影響。採用二氧化鈦、氟化鈉與奈米顆粒鑽石混合成不同比例之若干種活性助銲劑進行銲接研究,並選用針對鈦合金銲接的商用活性助銲劑ActivaTec860做為比較。添加1 wt%二氧化碳或是奈米顆粒鑽石比例在氟化鈉的活性助銲劑,可以有效地得到完全的熔貫穿深和造成晶粒細化的現象。添加1wt%的奈米顆粒鑽石在氟化鈉的活性助銲劑,融熔區與熱影響區的硬度較接近母材之硬度值,並呈現趨於平整的硬度分布。藉由穿透式電子顯微鏡,奈米顆粒對β相有粗化的現象,並且促進麻田散鐵α'的成核在β相上。 含鈦高強度低碳鋼經過惰性氣體遮蔽電弧銲接後,高溫肥粒鐵會在先前的奧斯田鐵晶界上成核,其高溫肥粒鐵的厚度會隨著輸入熱的提升而粗化。由顯微組織的觀察可發現高溫肥粒鐵、魏德曼肥粒鐵、針狀肥粒鐵,以及少部分的麻田散鐵、殘留奧斯田鐵或退化波來鐵、變韌鐵存在其中。因提高銲接電流也提升了銲接輸入熱,進而改善了銲道的融貫穿深。肥粒鐵晶粒內的差排密度,也隨著銲接輸入熱的增加而提升,並產生條紋狀的雙晶麻田散鐵。藉由提升輸入熱的銲接過程,觀察到肥粒鐵晶粒的碳化鈦並無明顯的析出成長。
The effects of nano particle containing activating fluxes on welding microstructure and hardness distribution of titanium alloy were investigated. The components of TiO2, NaF, and nano-particle diamond with different ratios were blended together into several kinds of fluxes. The fluxes consisting of NaF with 1wt% of either nano-TiO2 or nano-diamond effectively yielded refined grain size and deep weld penetration. The hardness of the weldment was close to that of the base metal for 99 wt% NaF plus 1 wt% diamond, leading to a desirable uniform mechanical property in the weld design. The transmission electron images illustrate that the nano particles affect the β phase coarsening and promote martensitic α´ phase formation at the β veins. The weld metal of titanium-bearing high-strength low-carbon steel reveals that the allotriomorphic ferrite on the prior austenite grain boundary coarsens with increased welding heat input. The welding penetration and depth-to-width ratio both increase with heat input from increased welding current. The solidified weld metal microstructures from various heat inputs exhibit the same microstructure constituents of allotriomorphic ferrite, widmanstatten ferrite, and acicuar ferrite. The dislocation density increases with higher welding heat-input. The dislocation morphology is obviously intertwined at the highest welding heat-input (3.0 kJ/mm). Twin martensite forms under different welding heat inputs, and the TiC precipitates in ferrite grain did not grow during the TIG welding process.
URI: http://ethesys.lib.ntou.edu.tw/cdrfb3/record/#G0M97720003
http://ntour.ntou.edu.tw/ir/handle/987654321/13912
Appears in Collections:[機械與機電工程學系] 博碩士論文

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