6056鋁合金具有優秀耐腐蝕性、高強度和良好的成形性，因此近年來常被用作汽車螺絲與扣件的材料使用。但在螺絲製造的過程中，打頭時的冷鍛加工由於變形量過大常常導致材料脆裂。因此，本研究為改善其加工性，對材料施以多種熱處理方法，並探討其冷軋延特性與拉伸機械性質的變化。另外，本研究亦會針對冷軋加工過後的材料，探討熱處理對冷軋材的微觀組織與拉伸機械性質的影響。
本研究中試驗材料分為六種：未經過任何熱處理的F材、經退火熱處理的O材、經固溶熱處理後淬水的W材、固溶熱處理後再195℃時效2小時的SPA195材、固溶熱處理後再230℃時效2小時的SOA230材、固溶熱處理後再250℃時效2小時的SOA250材。
實驗結果顯示，在上述的六種材料經過冷軋延至減變率85%時，SOA250材表現出最佳的冷軋延加工性，而工業上常用的O材則是由於退火熱處理無法消除組織中的粗大晶出物，使得冷軋延加工性沒有顯著改善。隨著時效溫度的提升，可以發現材料冷軋延加工性逐漸上升，並且內部硬度分布會變得更加均勻，這是因為時效使得基地中析出相粗化，使得冷軋加工時整體材料變形愈來愈均勻，進而提升臨界分解剪應力，故材料不易破裂。
由於SOA250材經過時效處理，雖然冷軋延特性提升，但強度和延性都大幅下降；而經冷軋延加工後，其強度提升有限。故本研究將冷軋延後的SOA250材再次進行T6熱處理，發現材料的拉抗強度可回復到約430 MPa，而總伸長率也回復到約23%，與進行過T6熱處理的原材相當。
本研究先將材料進行固溶熱處理和過時效處理獲得良好的冷軋延加工性，後續再施以T6熱處理得到優異的強度與延性，使材料符合車輛工業扣件應用標準。

6056 aluminum alloy which is designed to used in the automotive application because of the good corrosion resistance and high strength was carried out in this study. Although 6056 aluminum alloy had such good mechanical properties and formability, it’s surface cracked while applying the head forging process. Thus, the object of the experiment is improving the formability of 6056 aluminum alloy by using the pre-heat treatment. We got 5 different conditions of pre-heat treatment, annealing (O), solution treatment (W), aging in 195℃,230℃ and 250℃ for 2 hours after solution treatment (SPA195, SOA230 and SOA250).The experiment results showed that SOA250 had the best formability which can be compressed to reduction ratio 85% in diameter after cold rolling. O didn’t show good formability due to coarse second phase in the crystal. We could find out that the formability of 6056 aluminum alloy gets better with the rising temperature of artificial aging. According to the results of microhardness test, we could only surmise that there may be some relationship between formability and texture. Although SOA250 has good formability, it showed low strength and poor ductility after applying cold rolling. To improve the ductility and strength, we applied one more T6 treatment after cold rolling SOA250. The results showed that the ductility and strength was improved, and the mechanical properties of SOA250 after T6 is good enough to be used in automotive application.

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