Grain boundary precipitation of M23C6 in an austenitic steel

The dependence of carbide morphology on grain boundary character in the highly twinned Alloy 690

“…Most observations of other people's work showed that the carbide bars do not commonly connect with the incoherent twin boundary [5][6][7][8][9]14,31]. This is a misunderstanding due to the two dimensional observations.…”

“…Most of the observations of Refs. [5][6][7][8][9]14,31] are in two dimensional cross section of the carbide structure. If the observation cross section is parallel to the carbide bar as shown by plane 1 in Fig.…”

“…The morphology of grain boundary carbides has been extensively studied in face center cubic (FCC) structure Fe-Cr-Ni alloys [4][5][6][7][8][9][10][11][12][13][14], because grain boundary carbide precipitation has strong influence on the resistance to intergranular failures [11,[15][16][17][18][19][20]. Many studies [5,8,10,14,21] showed that the grain boundary misorientation can strongly affect the precipitation of chromium-rich carbide.…”

“…Low R (R 6 29) coincidence site lattice (CSL) grain boundaries have lower susceptibilities to carbide precipitation than random grain boundaries [10,[22][23][24]. Almost all of the reports [5][6][7][8][9][10]13,14,21] about carbide morphology in austenitic stainless steels and Alloy 690 showed that the morphology of carbides precipitated at twin boundaries is distinct from that precipitated at random grain boundaries. They showed that the platelike carbide precipitates can often be observed at the incoherent twin boundaries, while there is no such kind of carbide at other type boundaries.…”

Deformation Characteristics of Aluminium Composites for Structural Applications

“…Early work on growth kinetics has been developed for the grain boundary case [4] and for intragranular precipitation [5]. These approaches have been integrated to produce a unified description of the inter-and intra-granular nucleation and growth mechanisms [6,7]. More recently, successful attempts have been made to combine models of precipitate growth at interfaces with concurrently occurring segregation in aluminium alloys [8].…”