- 學位論文
鈦合金Ti-6Al-4V應用電漿銲之銲接性研究
A Study on Weldability of PAW for Titanium
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摘要
Ti-6Al-4V鈦合金是應用最廣泛的鈦合金，同時也是最早被開發之商用鈦合金。Ti-6Al-4V是典型α+β型鈦合金之代表，為目前使用量最大的鈦合金。近年來，隨著材料冶煉與加工技術漸趨成熟，鈦金屬的應用領域更為廣泛，是各界近年來積極開發的輕金屬材料之一。 本論文主旨在探討Ti-6Al-4V鈦合金在不添加銲料的方式下，進行鈦合金板材電漿對接銲再加氬銲對銲道表面進行重熔。此銲接方式為目前工業界常用之方法，其目的為消除鈦合金因板材過厚又或是接點附近因母材充填的不足，在電漿對接銲的過程中，發生過熔低焰(under cut)之現象。加上實驗出之最佳參數，探討鈦合金之銲接性，進而探討其機械性質，經過微硬度試驗、拉伸試驗、光學顯微組織觀察、掃描式電子顯微鏡觀察(SEM)、能量散佈光譜儀(EDS)進行分析探討，並對銲件實施施銲後熱處理，找出熱處理最佳參數，希望對Ti-6Al-4V合金能有進一步之瞭解，以期能改善鈦合金銲接性之各項問題。 研究結果顯示，利用PAW加TIG能成功銲接Ti-6Al-4V鈦合金，且能夠保證銲道不會有未熔透、裂縫、氣孔等銲接缺陷出現。Ti-6Al-4V鈦合金母材與銲後破斷面之顯微組織、銲件與銲件經退火熱處理後之拉伸破斷面之顯微組織，其破斷的位置皆在母材區域，且破壞處兩端均有頸縮現象，進一步觀察破斷面可發現韌窩狀組織與微小的空孔，綜合以上結果，故推斷破壞模式屬於延性破壞。而銲件經固溶加時效熱處理後之拉伸破斷面，其顯微組織是另一種與延性破壞完全不同的脆性破壞，脆性材料最明顯的特徵就是有劈裂的情形產生，這些裂痕都是沿著晶界生長，存在裂縫生成與延伸的區域，由此方法分析，破壞模式應是脆性破壞。 熱處理試驗取Ti-6Al-4V鈦合金熱處理最佳參數範圍之最大與最小溫度值，作為本研究之實驗參數，結果顯示退火熱處理最佳參數為720C(2 hr)，空冷至室溫。而析出熱處理則是固溶熱處理925C(10min)，水冷；時效熱處理535C(4 hr)，空冷。
並列摘要
Ti-6Al-4V Titanium is the most widely used titanium alloy, it is also the first to be developed commercial titanium alloys. Ti-6Al-4V is a typical α + β type titanium alloy of the representatives, it is also the largest capacity of currently used titanium alloy. In recent years, as long as the processing technology matured, wider application of titanium, it is one of the development of light metal materials. This study focuses on the Ti-6Al-4V titanium alloy in the solder manner without adding. For titanium alloy sheet used PAW welding added TIG welding on the surface remelting. This welding method for the current methods commonly used in industry. The aim of titanium due to plate too thick or near the junction due to lack of base metal filling, In the welding process of under cut the situation. Experiment with the best parameters of the welding of titanium alloy then to study their mechanical properties. Through tension testing, hardness testing, optical microscope, scanning electron microscope, energy dispersive spectrometers. And implementation of treatment, identify the optimal treatment parameters, want to Ti-6Al-4V alloy can further the understanding, in order to improve the problem of welding titanium. The results show that the successful use of PAW welding add TIG welding Ti-6Al-4V titanium alloy. Can guarantee there will be no weld cracks, cavities and other weld defects occur. Titanium alloy, the fracture location of all the base metal region. Further observation can be found in the fracture surface dimple-like organization with tiny air holes, the above results, it is inferred failure mode is ductile fracture. The other is brittle, the most obvious feature is a split condition. Test taking Ti-6Al-4V titanium alloy heat treatment the best range of parameters the maximum and minimum temperature, as the study of experimental parameters. The results showed that the optimum parameters of annealing is 720℃(2hr) air cooling, Solution heat treatment is 925℃(10min) water cooling, Heat treatment 535℃(4hr) air cooling.
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