Co-operative and site-competitive interaction processes at the grain boundaries of a Ni-Cr-Mo-V steel

Nonequilibrium grain-boundary cosegregation of nitrogen and chromium in NiCrMoV steel

“…The interaction between Cr and N is more apparent when the ratio of the coverages of Cr and N is plotted with respect to time, as shown in Figure 2. [22,23] The mean value is about 1.0, independent of time. This gives strong evidence to the cosegregation of Cr and N.…”

“…Experimental Cosegregation Isotherms of Cr and N [22,23] Misra et al [22,23] have employed the technique of AES to measure grain-boundary segregations as a function of time in the temperature range of 700 to 900 K. The chemical composition of the NiCrMoV steel they used is given in Table I, and the measured segregation isotherms of elements are shown in Figures 1(a) through (d). The data presented in these figures are expressed in terms of normalized peakto-peak height (normalized with respect to Fe), H x .…”

“…Misra et al [22,23] have pointed out that the parallel segregation isotherms of Cr and N are cosegregation and that they can be attributed to the interaction between the pair of cosegregating elements. The interaction between Cr and N is more apparent when the ratio of the coverages of Cr and N is plotted with respect to time, as shown in Figure 2.…”

“…Among different pairs of cosegregating elements, the cosegregation of Cr and N has been paid much attention by researchers, [18][19][20][21][22][23][24][25][26][27] even when found in a Ni-based alloy. [28] In References 21 through 23, Misra et al have demonstrated the cosegregation of Cr and N using the isotherms, but have not elucidated whether the cosegregation is equilibrium or nonequilibrium.…”

“…[28] In References 21 through 23, Misra et al have demonstrated the cosegregation of Cr and N using the isotherms, but have not elucidated whether the cosegregation is equilibrium or nonequilibrium. In the present article, based on the model of NGCS [12,13] the cosegregation processes of Cr and N were analyzed in terms of the observations in a commercial NiCrMoV steel by Misra et al [22,23] The analyses show that the cosegregation of Cr and N are NGCS.…”