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Please use this identifier to cite or link to this item: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/29752

Title: Ti-6Al-4V與Ti-15V-3Cr-3Al-3Sn 銲件之高溫缺口拉伸性質研究
Notched Tensile Fracture of Ti-6Al-4V and Ti-15V-3Cr-3Al-3Sn Welds at Elevated Temperatures
Authors: Mei-Yuan Lu
陸美源
Contributors: NTOU:Institute of Materials Engineering
國立臺灣海洋大學:材料工程研究所
Keywords: 缺口拉伸試驗;Ti-6Al-4V;Ti-15V-3Cr-3Al-3Sn;雷射銲接;銲後熱處理
notched tensile test;Ti-6Al-4V;Ti-15V-3Cr-3Al-3Sn;laser welding;post-weld heat treatment
Date: 2011
Issue Date: 2011-11-23T03:13:07Z
Abstract: 本研究主要探討使用5KW二氧化碳雷射對Ti-6Al-4V及Ti-15V-3Cr-3Al-3Sn合金板材進行銲接,比較板材與銲件經不同時效熱處理之試件,評估兩種鈦合金在不同溫度環境下其缺口拉伸性質之變化情形。 在室溫、150℃、300℃及450℃環境下,對Ti-6Al-4V母材與經不同時效熱處理之銲件,進行缺口拉伸試驗。結果顯示,Ti-6Al-4V母材隨環境溫度的升高,其缺口拉伸強度隨之下降及延性增加; Ti-6Al-4V銲後原始狀態與經482℃與704℃時效處理之銲件,整體高溫缺口拉伸強度之趨勢與母材相似,缺口拉伸強度隨環境溫度升高而下降及延性增加。由缺口拉伸破裂面微觀特徵顯示,Ti-6Al-4V母材呈現延性細小窩穴狀破裂,隨環境溫度升高,有較大且深之窩穴狀破裂特徵,Ti-6Al-4V銲後原始狀態與經482℃時效處理銲件於室溫下為延性穿晶與部分類劈裂破壞,隨環境溫度提高,破裂型態轉變為延性穿晶破裂,而經704℃時效處理銲件,室溫下穿晶窩穴狀及沿晶破裂,隨環境溫度提升,沿晶破裂型態有增加之趨勢。 Ti-15V-3Cr-3Al-3Sn經不同時效熱處理之板材與銲件在室溫下,除銲後原始狀態外,其餘時效處理之板材缺口拉伸強度皆高於時效處理銲件,經593℃時效處理之試件有最高之缺口拉伸強度;環境450℃時,板材經時效處理之缺口拉伸強度皆高於經時效處理之銲件缺口拉伸強度。從缺口拉伸破裂面顯示,室溫下Ti-15V-3Cr-3Al-3Sn原始板材為類劈裂脆性破裂與銲後原始狀態之延性穿晶窩穴狀破裂不同;在高溫450℃時,各時效處理之板材與銲件其破裂型態主要皆為延性穿晶窩穴狀破裂。
In this work, the notched tensile strength of Ti-6Al-4V and Ti-15V-3Cr-3Al-3Sn laser welds subjected to different post-weld heat treatments (PWHTs) was determined and compared with that of the mill-annealed base metal (MB). Notched tensile tests of Ti-6Al-4V laser welds, were subjected to post-weld heat treatments (PWHTs) at 482oC or 704oC, were carried out in air at 25, 150, 300 and 450oC. The results were compared with those of mill-annealed base metal (MB) specimens tested at same temperatures. In general, the notched tensile strength (NTS) of all specimens decreased with increasing temperature. The results indicated the NTS of the MB specimen was obviously higher than that of the welds at room temperature, but became much lower at 450oC. It was deduced the presence of thicker grain boundary α promoted intergranular fracture at elevated temperature accounted for the decreased NTS of the weld with the PWHT at 704oC. However, the notched tensile tests of Ti-15V-3Cr-3Al-3Sn laser welds, which were subjected to post-weld heat treatments (PWHTs) at 371oC、426oC、482oC、538oC and 593oC, were carried out in air at 25oC and 450oC. Notched tensile strength of all welds are higher than all aging plates. At 25oC, the MB specimen shows cleavage-like fracture. In contrast, the transgranular dimple fracture was observed in as-welded specimen. With the elevated temperature arising to 450°C, the fracture morphology of all conditions present transgranular dimple fractures, could be attributed that the ductility of the material shows markedly increase at high temperature.
URI: http://ethesys.lib.ntou.edu.tw/cdrfb3/record/#G0M98550001
http://ntour.ntou.edu.tw/handle/987654321/29752
Appears in Collections:[材料工程研究所] 博碩士論文

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