鋁合金在室溫下成型性不佳，故在塑性加工前常使用退火處理提升材料延性以利加工，而近年有文獻提出可用固溶處理取代退火處理。另外，本實驗使用經6069改質後的6042鋁合金，固溶量多寡與後續析出效應將影響合金機械性質。故本實驗第一部份探討退火與固溶熱處理對材料性質影響，第二部份探討合金不同固溶量效應，第三部份藉由預應變實驗綜合前兩部份實驗結果。
第一部份實驗結果顯示O處理保留了F材原始組織，W處理呈現粗大化晶粒，O材與W材拉伸曲線皆發生動態應變時效，拉伸性質上O材雖有較低強度，但W材有較高均勻延伸率與加工硬化率。以成型角度而言，W材較適合作為6042鋁合金管材加工前的熱處理。
第二部份固溶量效應方面，不論是空氣爐固溶溫度或是鹽浴爐固溶時間的改變，合金強度與硬度隨固溶量增加而提升，其中空氣爐製程之過高溫固溶583-T6材有最大拉伸強度，其破壞機制為沿晶破壞。另外，鹽浴爐salt(5)-T6材與空氣爐555-T6材有類似微觀組織、硬度與拉伸性質，表示鹽浴固溶5分鐘已具空氣爐固溶30分鐘效果。
預應變實驗方面，以鹽浴5分鐘作為固溶熱處理並進行預拉伸後，不論是直接施以190℃-6 hr時效或重新施以salt(5)-T6熱處理，材料強度均有良好表現，其中，salt(5)-20％-salt(5)T6材有較佳拉伸強度。
檢討各熱處理製程對6042合金微觀組織與機械性質之影響後可發現，W材適合應用於塑性加工的前處理，而固溶效應方面，鹽浴555℃-5 min固溶已可讓大部份Mg2Si固溶回基地並可作為管材成型前的W處理，且W材預應變後可直接施以人工時效處理，或是重新施以T6處理(固溶加人工時效)提升材料機械性質。

6042 tube aluminum alloy (modified from AA6069) was used in this study. This alloy was developed to be applied to high strength and low weight bicycle frame, so there are two objective in this study. First, we hope to obtain above 30 % uniform elongation and high work hardening rate of 6042 tube aluminum alloy before plastic process. In order to improve formability for 6042 tube aluminum alloy, annealing (O) and solution treatment (W) were conducted. Second, we expect to attain high strength (400 MPa) and 10 % total elongation after different heat treatments including T6 treatment and pre strain-post heat treatment after W. In T6 treatment, we studied the effect of different solution temperature. Besides, to reduce solution time, we also investigated the effect of different solution time in salt bath process.
In the first part, results showed that both O and W had above 30 % uniform elongation. However, the strain hardening exponent (n) and work hardening rate of W is higher. From the formability point of view, W is more proper before plastic process. In the second part, 583-T6 had the highest strength but accompanied severe intergranular fracture. It means over heated solution treatment (583-T6) cannot be applied to bike frame due to safety concern. In salt bath process, solution time could be reduced to 5 min compared to air furnace (30 min).And in the third part, strength of W after pre-strain could be improved by different post heat treatment, especially in salt(5)-20％-salt(5)T6.

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