Incoloy 800H銲件在950℃乾空氣環境之循環氧化行為研究

The Cyclic Oxidation Behavior of Welded Inconel 800H Superalloy at 950 ℃ in Dry Air

本研究探討Incoloy 800H經銲接處理後之基材（800H-SUB）、熱影響區（800H-HAZ）及銲道（800H-MZ）三種區域在950℃乾空氣下的循環氧化行為。研究結果顯示，合金經20次循環之氧化速率由快而慢依序為800H-HAZ > 800H-SUB > 800H-MZ。由SEM及XRD分析得知，氧化後三種區域皆生成兩層氧化層，其中，800H-SUB與800H-HAZ兩者內層主要生成Cr2O3及(Fe,Cr)2O4，外層主要生成Fe2O3和Fe3O4；然而800H-MZ氧化後外層生成MnCr2O4及(Ni,Cr)3O4，內層氧化層則為Cr2O3；推測母材中Mn離子的外擴散所形成MnCr2O4是800H-MZ合金氧化速率較慢的主因。

The cyclic oxidation behavior of three different zones of welded Incoloy 800H, containing the substrate (800H-SUB), the heat-affected zone (800H-HAZ) and the melt zone (800H-MZ), was studied at 950 ℃ in dry air. The results showed that the oxidation-resistant ability of the alloys after the 20-cycle followed by the rank from fast to slow of 800H-HAZ > 800H-SUB > 800H-MZ. The scales formed on the 800H-SUB and 800H-HAZ consisted of a heterophasic mixture of Cr2O3 and FeCr2O4 in the inner layer, as well as Fe2O3 and Fe3O4 in the outer layer. Duplex scales also formed on 800H-MZ consisted of an outer layer of MnCr2O4 and small amount of (Ni,Cr)3O4, and an inner layer of Cr2O3. The MnCr2O4 formation by Mn ion outer diffusion was responsible for the slow oxidation rate of 800H-MZ.