T92對304H合金異種銲接之碳遷移研究

The Study of Carbon Migration in T92-304H Dissimilar Weldment

10.6342/NTU201900723

黃玄根

異質銲接 ； 鎳基填料 ； 碳遷移 ； 老化實驗 ； 軟區 ； Dissimilar welding ； Nickel-based filler ； Carbon migration ； Aging test ； Soft zone

國立臺灣大學材料科學與工程學系學位論文

2019年

碩士

薛人愷

繁體中文

本實驗使用不同填料 ( Inco 82、309L) 進行 T92 與 304H 異質氬銲製程。銲件經過非破壞性檢測後，將合格銲件用線切割的方式取出銲道部分並進行銲後熱處理。實驗中主要探討鋼材在異種銲接時所發生的碳遷移 (carbon migration) 現象。由於碳的含量會影響到合金在該處的硬度值，所以發生碳遷移的位置，會有一低碳軟區 (soft zone)。此區域可以經由光學顯微鏡及硬度值的變化發現。此 soft zone 產生會影響到銲道附近的機械性質。實驗結果發現，當銲道填料使用 Inco 82，經過長時間老化實驗後，銲道兩側介面處沒有鉻濃度的差異，沒有造成碳原子的擴散，所以並沒有發現 soft zone。若填料使用 309L，經過長時間老化實驗後，在銲道與 T92 交界處有鉻濃度的差異，造成碳原子的能量不同，產生 soft zone。 隨著老化時間的增長，soft zone 的區域也會持續長大。此外 soft zone 區域的硬度值大幅降低，可預期銲件機械性質與高溫應用之可靠度將明顯的降低。

In this experiment, different fillers (Inco 82, 309L) were used for T92 and 304H dissimilar TIG (Tungsten Inert Gas) welding. After the non-destructive (NDT) inspection of the weldment, the qualified weldment was machined by wire cutting and subjected to post-weld heat treatment. Because the content of carbon will affect the hardness of the alloy, so the location of carbon migration will produce a low carbon soft zone (soft zone). This area can be found in optical microscope obserration and hardness values. The production of soft zone will affect the mechanical properties near the weld pass. The results of the experiment show that the filler Inco 82, after a long aging experiment, the interface between the two sides of the weldment does not have the difference of chromium concentration, no carbon atom diffusion, so no soft zone produced. If the filler uses 309L, after a long aging experiment, the difference of chromium concentration at the interface between the weldment and the T92 leads to the different diffusion energy of the carbon atom and produces soft zone. As the aging time increases, the area of soft zone will continue to grow. In addition, the hardness of soft zone will be significantly reduced, resulting in deteriorated mechanical properties and high temperature reliability in application.

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