PSI - Issue 14

Neeta Paulose et al. / Procedia Structural Integrity 14 (2019) 649–655 Neeta Paulose etal./ Structural Integrity Procedia 00 (2018) 000–000

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3. Results

3.1 Microstructure The as cast CF 8C shows dendritic structure (Fig.1a) It is reported by P.L. Ferrandini et al. (2006) that if the alloy has 1.48 < Cr equ / Ni equ < 1.95, then the solidification begins with the formation of ferrite and the remaining liquid becomes rich in ϒ stabilizer during the solidification transforming into austenite. Hence, the final microstructure at the ambient temperature includes δ (delta phase) as a primary phase within the dendritic arms enveloped by the  (austenite phase). Similar structure is seen here (Fig.1b)

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b

Fig.1 (a) CF 8C (as cast) showing dendritic structure (b) CF 8C (as cast) showing δ ferrite (dark) and ϒ (light phase)

Fig.2 shows microstructure of as cast CF 8C at higher magnification studied using SEM. It reveals δ ferrite pools and carbides on austenite matrix. Similar microstructure of CF 8C is reported by J.P.Shingledecker et al. (2006)

Austenite matrix

Carbides

δ Ferrite

Fig.2 As cast structure at high magnification

In as-cast structure of CF 8C, the pools of δ ferrite are spread almost continuously in austenite matrix (Fig. 3 a). In