本研究主要以GTAW對不同熱處理後之鎳基600合金進行對接銲，探討銲件熱影響組織微結構的改變及其耐蝕性的變化。並藉由量測銲接入熱量與銲接熱循環，分析銲接溫度之分佈對銲件組織變化的影響。實驗所選用的素材原始狀態為應力消除退火（843℃/1h, Stress Relief）處理，之後分別施以熱時效處理（700℃/24h, Thermal Treatment）及固溶化處理（1100℃/0.5h, Solution Annealing）後進行銲接。
　　實驗結果顯示，由微結構觀察可發現，SR試件晶界上析出一層連續的細薄碳化鉻，TT(700℃/24h)試件晶界上之析出物為半連續的碳化鉻，SA(1100℃/0.5h)試件晶界上則沒有明顯析出物產生。SA與TT素材耐蝕性較佳，而SR試件耐蝕性差，其中腐蝕型態皆以沿晶腐蝕為主。
觀察銲接後之銲件組織，僅SA銲件有銲接衰化區產生，此區發生嚴重沿晶腐蝕導致晶粒剝落，根據熱循環曲線顯示，衰化區於銲接時通過敏化溫度（500~750℃）之時間皆為10秒以上之區域，而冷卻速率約為25~32℃/秒，沿晶界有碳化鉻連續狀態析出，導致銲件抗沿晶腐蝕能力下降而形成銲接衰化區。TT銲件並無明顯的銲接衰化區產生，實驗結果顯示適當的TT熱處理後能有效抑制銲接衰化區的出現。SR銲件雖然沒有觀察到明顯的銲接衰化現象，但其母材之耐蝕性非常差，經過24小時Huey Test腐蝕後，晶粒剝落至幾乎粉碎狀態。
本實驗利用銲接熱循環量測技術對SA銲件衰化區之預測，可簡單估算出銲接衰化區產生的位置及大概的範圍，搭配後續之銲後熱處理及表面重熔等技術，可事先預防可能發生的破壞情形。

This study investigated the microstructure and corrosion resistance of Inconel 600 Alloy weldments by GTAW process. The heat treatments of As-received Alloy 600 were stress relieved (SR) at 843℃ for 1 hour. Then Alloy 600 were treated with solution annealed (SA) at 1100℃ for 30 min and thermal treatment (TT) at 700℃ for 24 hours. Their corrosion resistance was evaluated by Huey test.
Compared to the microstructure in the heat affected zone of these weldments, there was weld decay zone in SA weldment. According to the temperature measurement, it took over 10 seconds to pass through the sensitization range (500~750℃), and the cooling-rate of this zone were between 25~32℃/sec. Cr-carbides precipitate along the grain boundary, and hence to decrease the corrosion resistance in this zone. There was, however, different microstructure in TT weldment. Because of TT heat treatment, Cr-depletion zone has recovery. This effect can prevent weld decay zone forming during welding. SR weldment has poorer corrosion resistance of base metal than the other two. Serious Intergranular corrosion happened (IGC) after 24 hours Huey test.
We may predict weld decay zone in SA weldment by welding thermal cycle. The weldment could be repaired to prevent rupture.

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