由於鋁合金具備質輕、易加工、耐蝕性與抗氧化性佳等優點，在工程結構及民生用品上被廣泛的應用。而在各種用途上涉及銲接技術者佔大部分，因銲接而引發之問題對鋁材之機械性質有關鍵性的影響，也唯有靠適當的銲接技術與銲後處理，才能有效改善與消除上述之影響，使銲件品質達到業界之需求。故本研究針對運輸業中廣泛使用之了7003與工業界常見之6061鋁合金為主題，應用惰性氣體鎢極電弧銲，配合非熱處理型ER5356銲線為填料施以平頭對接。銲後經由各種不同之熱處理，並藉由拉伸試驗、金相組織觀察、微硬度測試與SEM破斷面觀察四項測試結果為指標，以探討銲接與熱處理前後機械性質與微觀結構之變化並分析其成因，再由其中選定較佳之熱處理參數，以謀求改善之道。
經實際測試與觀察中發現：鋁材7003與銲件7003-7003經人工時效處理後，抗拉強度與硬度均明顯降低，若將時效時間延長，上述情形將更加惡化。而後者之熱影響區，由於施銲中熱傳而產生部份固溶，經人工時效後導致硬度上揚至接近原母材，但對整體機械性質助益不大。此銲件若施以全程熱處理後，除銲道部位外，其餘銲件各部位之強度與硬度均大幅提昇，超過原母材水準，可有效改善銲後機械性質。銲件7003-6061經前述之人工時效處理後，在6061部位之熱影響區，強度與硬度均明顯下挫。若將時效時間延長，情形更為明顯，不論強度與硬度均維持在最低檔位置，不因人工時效而有翻揚之跡象。而此銲件經過全程熱處理後，除銲道部位外，其餘部位之強度與硬度均大幅上揚，甚至超過原母材，此法可有效消除銲後軟化之現象。此外，在SEM觀察結果顯示，不論歷經何種熱處理，銲件之破斷面均呈現延性破壞之現象。

Because the characteristics of low weight, easy formability, good corrosion resistance and oxygen resistance, aluminum alloy have been applied extensively in engineering structures and life appliances. Some problems obtained from welding process can heavily influence the mechanical properties of aluminum alloy weidment. The problems can be eliminated only by proper welding skills and post weld heat treatments. Therefore, the quality of weldrnents can be satisfied by the industrial demands. The purpose of this research was to systematically study the weldability of aluminum alloy under Tungsten Inert Gas Arc Welding. The base metal used were 7003 and 6061 with filler metal of ER5356 which is non heat treatable. Different post weld heat treatments, tensile test, optical metallography, microhardness test and SEM observation were used to determine and analysis the relationship between properties and microstructures.
The test results and observations indicated that both the tensile strength and hardness were decreased after artifical aging treatment for 7003-7003 weidment. It became more serious for prelonged time. Partial solution have been occured in HAZ by heating during welding process. Artifical aging only can not improve the mechanical properties. The strength and hardness can be increased even over that of base metal after full treatment. The properties of fusion zone can not be improved by the full treatment. Same results also obtained for 7003-6061 weidment. Artifical aging-process can not enhance the hardness in HAZ for 6061 weldment. The results will be better with filler which is heat treatable. Again, the full treatment can enhance the overall properties of 7003-6061 weidment except the fusion zone. In addition, the result from SEM observations indicated that ductile fracture occured in all weidments no matter what heat treatment.