V(C, N) inclusion in Low C–Mn

V(C, N) inclusion in Low C–Mn–V steel

Figure 1: Identification of V(C, N) acting as nucleation sites for AF in 5B steel. T(gamma)=1125°C, zones 1 and 2 correspond to a cooling rate of 10°C/s, zone 3 to a cooling rate of 4°C/s. SEM, scale bars: 1, 0.5 µm.

Inclusion name: V(C, N)
Record No.: 860
Inclusion formula: V(C, N)
Inclusion type (Macro/Micro/Nano): Micro
Inclusion type (Exogenous/Indigenous): Indigenous
Inclusion classification: Carbonitride
Inclusion composition in weight %: No data
Sample: Low C–Mn–V steel
Steel composition in weight %: 0.08% C, 1.46% Mn, 0.25% V, 0.0180% N, 0.016% Al, 0.007% Si, 0.001% S.
Note: For 5B steel cooling at 10°C/s from 1125°C Fig. 1 shows an AF nucleus at an almost pure V nitride, zone 1. Analysis in zone 2, matrix, helps to confirm that most ofthe C detected in zone 1 corresponds to the matrix and also that the Mn detected in zone 1 corresponded to the matrix and not to a MnS associated with the V precipitate. Zone 3, for the same steels but a cooling rate of 4°C/s, corresponds to an active V nitride from where an AF (accicular ferrite) plate has nucleated. The fact that the precipitates are almost pure V nitride confirms that both precipitated in the austenitic state i.e. previous to the formation of AF.
Reference: Not shown in this demo version.