本研究目的係尋求適用於AA7005鋁合金之最佳銲後熱處理製程，並探討銲條類型對銲後熱處理製程之影響。將AA7005-T1母材應用ER5356、ER5183及ER5556等高鎂含量銲條銲接，再施以自然時效、T6、T73及RRA等熱處理製程，從金相組織、微硬度試驗、拉伸試驗、EPMA、SEM、TEM、DSC與應力腐蝕測試等方面，探討不同銲條與銲後熱處理製程之組合對銲件之微觀結構及機械性質的影響，期能找出具有高抗拉強度與高抗應力腐蝕能力之銲後熱處理製程。
實驗結果顯示，經三種銲條銲接所得之工件在銲道與熱影響區界面間均會形成擴散障礙層，ER5356銲接所得工件其擴散層較ER5183及ER5556所得銲件要來得寬廣。ER5356所得銲件經固溶處理後，此擴散障礙層已不存在。惟ER5183及ER5556所得之銲件雖經固溶及時效熱處理，此擴散障礙層變寬（從0.25mm到0.5mm），但無法消除，阻擋銲道與母材間鋅、鎂二元素的相互擴散機制，以致在銲道無法形成強化相η’(MgZn2 )發揮析出強化的功能。導致此種差異之可能原因為ER5183與ER5556所銲之銲道在銲接過程中或固溶熱處理時，其高錳鎂含量易與鋁基材析出Mg2Al3、MnAl6及(MgMn)3Al10等非強化相，造成銲件整體之抗拉強度無法提昇。為探討熱處理製程對AA7005銲件機械性質之影響，AA7005鋁擠材應用三種銲條所得銲件進行熱處理後，惟ER5356所銲之工件能提昇銲件整體強度，其中以 RRA製程最能提昇銲件整體強度，而T73製程能使銲道強度高於母材強度。故應選擇T73製程作為最佳銲後熱處理製程。

Proper fillers selection and postweld heat-treatment can strongly affect the mechanical and stress corrosion cracking (SCC) properties of the weldments of 7000 series aluminum alloy. ER5183, ER5356 and ER5556 having similar chemical compositions are the three fillers commonly used for AA7005 welding process. The objective of this study is to investigate the influence of alloying elements on the postweld heat-treatment process and to select suitable postweld heat-treatment processes for AA7005 aluminum alloy.
Postweld heat-treatment processes, such as nature aging, T6 temper, T73 temper and RRA treatment, will be performed. Optical metallographic, micro-hardness test, tensile test, EPMA, SEM, TEM, DSC and SCC test will be conducted to characterize the mechanical and stress corrosion properties of these heat-heated weldments.
Experimental results showed that diffusion barriers are presented between the weld metal and HAZ fell on ER5556, ER5183 and ER5556 weldments. The diffusion barrier fell away after solution treatment on ER5356 weldments ,but the same situation did not happened on ER5183 and ER5556 weldments; because this barrier, Zn and Mg could not diffuse between the weld metal and HAZ ,in which the precipitates η’(MgZn2 )which are not extremely fine and distributed inside the grains on the weld metal , and the high content of Mg and Mn which are caused to form Mg2Al3,MnAl6 and(MgMn)3Al10 on the welding process or solution treatment on weld metal; these precipitates cause large particles barriers to the mechanical properties on ER5183 and ER5556 weldments. The strength of AA7005 weldments with ER5356 filler may largely increases after RRA heat-treatment. It can be concluded that T73 heat treatment is the most suitable postweld heat-treatment process for AA7005 aluminum alloy comparing with the other treatment processes.

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