The relative abundance of the alloying elements in the phases is in
wt%. Note that the EDX composition simply shows the relative abundance
of the alloying elements within an area in the phase and has no direct
relationship with the steel overall composition shown in Table 2. In
Fig. 5(b to d), locations 1, 3, 4, 16, 21, 30, etc., are areas of
analyses on the αHR , while 2, 5, 17, 25, 28, etc.
are areas on the αLR . The light etching is theP , e.g. locations 6, 7, 8, 13, 26 etc. In Table 3, simple
observation of the EDX results show that the alloying compositions
of αLR andαHR are almost the same. But for theαHA , all other alloy compositions are generally
the same with that of αLR andαHR except that the amount of C, Si, Al and O are
higher. The Fe content of αHA and P are
close, but lower than those of αLR andαHR . This tends to suggest thatαHA is a ferrite phase with the highest
concentration of alloying solutes. The P is found to have
generally the same composition with the αHA , but
with higher oxygen content. An important note here is that the
concentration of these solutes may weaken this phase, making it an easy
path for FCG . General
observed phase morphologies of J2N, G8 and G10 are shown in Fig. 6. Fig.
6 (a & b) are that of J2N obtained in the through thickness direction.
The same basic microstructural features as presented in Fig. 5(a) were
also observed in Fig. 6 (a & b). Fig. 6(c to i) present microstructural
features in the TMCP steels which are basically the same as that
found in the J2N steel. For the TMCP , the \(P\) formed mainly
between boundaries of the ferrite grains and with width that is
relatively small. In the NR steel, \(P\) forms as dense and
blocky phase in the αmatrix.