Nonequilibrium Grain Boundary Segregation of Sulfur and Its Effect on Intergranular Corrosion for 304 Stainless Steel

Wang, Kai; Xu, Tao; Shao, Chong Xiao; Yang, Chun

doi:10.1016/s1006-706x(11)60079-4

Cited by 10 publications

(10 citation statements)

References 19 publications

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“…Furthermore, Ni and Mn atoms evidently segregate to the interfaces between the Cu-rich phase and the α-Fe matrix, while C, P, Mo, Si atoms prefer to segregate towards the α-Fe matrix near the interfaces, but their segregation amount at the interfaces of Cu-rich phase and the α-Fe matrix is less than that at the grain boundaries. ¡¹Å Þ [1] ¡±Î³ [2] ¡¸ [3] ¡ß [4,5] ¡ [6,7] Ã [8,9] ³Ò . µ ¶ Ö ¶Ø ¦ ¦ ÒÀ¡ ¦ ÂÃ ¼ ¥Ú³, Í¤¡¹Å ³¢³Ò [10,11] .…”

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confidence: 99%

Segregation of Atoms on the Interfaces in the RPV Model Steel Studied by Apt

Lin-Ling²,

Liu³

et al. 2013

ACTA METALLURGICA SINICA

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The segregation of impurity or solute atoms to grain boundaries as well as phase interfaces can either improve or degrade the chemical, physical and mechanical properties of alloys. This phenomenon has been studied widely for iron based alloys, and the analysis method by an atom probe tomography (APT) is a powerful tool for better understanding this problem. The resulting composition changes of grain boundaries and phase interfaces, as well as the precipitation of Cu-rich nanophases, are frequently associated with the phenomenon of embrittlement in ferritic reactor pressure vessel (RPV) steels. The present work was carried out to study the segregation of impurity or solute atoms to grain boundaries as well as phase interfaces in a RPV model steel with higher content of Cu (0.53%, atomic fraction) than commercially available one. The RPV model steel was prepared by vacuum induction melting. The specimens were further heat treated by water quenching at 880 ¢ for 30 min and tempering at 660 ¢ for 10 h, and finally aged at 370 ¢ for 3000 h. The results show

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confidence: 99%

Segregation of Atoms on the Interfaces in the RPV Model Steel Studied by Apt

Lin-Ling²,

Liu³

et al. 2013

ACTA METALLURGICA SINICA

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“…Table 4 lists the critical time of S TNGS in the 304 stainless steel calculated by equation ( 2). 104 It is evident that the critical time of S is about 3?5 h at 815uC and 20 h at 732uC respectively. Both correspond to the sensitising time of corrosion embrittlement peaks at 815 and 732uC respectively.…”

Section: Intergranular Corrosion Embrittlementmentioning

confidence: 94%

“…Similarly, the critical time of 1690 h at 565uC is close to the sensitising time of 1500 h. Therefore, a corrosion embrittlement peak occurs at the sensitising temperature of 565uC for samples sensitised for 1500 h at different temperatures. Based on these observations, Wang et al 104 concluded that the ICE peaks in Stickler and Vinckier's experiments are induced by the TNGS peak temperature of S.…”

Section: Intergranular Corrosion Embrittlementmentioning

confidence: 97%

“…14 and 15 is induced by the critical time of S TNGS. 104,105 Embrittlement peak temperature It may be noted from Fig. 14 that after a 450 h exposure to Strauss solution, a corrosion embrittlement peak indicated by medium cracking (2 in Fig.…”

Section: Intergranular Corrosion Embrittlementmentioning

confidence: 99%

“…The critical times of S TNGS calculated by equation (2) 104 are summarised in Table 4 for the 304 stainless steel aged at different temperatures after quenching from a solution temperature of 1260uC, which is the same as Sticker and Vinckier's heat treatment cycles. 9 The critical time of 20 h at 732uC is the closest to the sensitising time of 15 h. Thus, a corrosion embrittlement peak occurs at the sensitisation temperature between 732 and 649uC for all the samples sensitised for 15 h at different temperatures.…”

Section: Intergranular Corrosion Embrittlementmentioning

confidence: 99%

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Unified mechanism of intergranular embrittlement based on non-equilibrium grain boundary segregation

Liu

Wang

et al. 2013

International Materials Reviews

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The review is aimed at presenting a unified approach in understanding the mechanism of nonequilibrium grain boundary segregation, which can satisfactorily describe the three types of intergranular embrittlement, namely, reverse temper embrittlement of steels, intergranular corrosion embrittlement of stainless steels and intermediate temperature embrittlement of metals and alloys. The review starts with a broad perspective of non-equilibrium grain boundary segregation, including thermally induced non-equilibrium grain boundary segregation and stress induced non-equilibrium grain-boundary segregation. Next, it focuses on the recent progress made in the non-equilibrium grain boundary segregation, including (1) critical time, (2) segregation peak temperature, (3) segregation peak temperature movement for thermally induced and stress induced non-equilibrium grain boundary segregation, and (4) the effect of temperature difference on thermally-induced non-equilibrium grain boundary segregation. Next, the attention is focused on the grain boundary coverage of elements and intergranular embrittlement phenomena. Three types of intergranular embrittlement is analysed in terms of (1) the ductility healing effect induced by the critical time, (2) embrittlement peak or ductility trough induced by the segregation peak temperature, (3) embrittlement peak or ductility trough movement induced by the segregation peak temperature movement and (4) widening and deepening of ductility trough induced by differences in temperature. These experimental phenomena concerning the three types of intergranular embrittlement are consistent with the models of thermally induced and stress induced non-equilibrium grain boundary segregations of impurities, instead of precipitation or equilibrium grain boundary segregation. Towards the end, we visit the subject of grain boundary segregation and associated embrittlement process from the viewpoint of fracture resistance and briefly discuss different perspectives that are of practical significance. List of symbolsA constant b the Burger's vector B Norton coefficient C b (t c ) grain boundary concentration at critical time C b(s50) equilibrium concentration of solute at the grain boundaries C g concentration of solute within the grains C v s~0 ð Þ equilibrium vacancy concentration at grain boundaries C v s~s ð Þ grain boundary vacancy concentration induced by the tensile stress D b the diffusivity D c diffusion coefficients for complexes under or in absence of applied tensile stress D i diffusion coefficients for solute atoms under or in absence of applied tensile stress E the elastic or Young's modulus -E the embrittlement sensitivity in K/at-% of solute at the grain boundary E b formation energy of vacancy solute atom complex International Materials Reviews 2013 VOL 58 NO 5263 E f vacancy formation energy E gb the elastic or Young's modulus of grain boundary region F v the formation energy of a vacancy in the boundary region H Z intergranular Auger peak to peak height of an element normalised with the ...

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