Two types of boron segregation at austenite grain boundaries and their mutual relation

Xu, Tao; Song, Shenhua; Zhexi, Yuan; Zhou, Yu

doi:10.1007/bf01045378

Cited by 18 publications

(8 citation statements)

References 5 publications

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“…It possesses excellent corrosion and oxidation resistance in addition to superior tensile and creep properties at elevated temperatures. [10][11][12][13][14][15] In equilibrium segregation, boron atoms that diffuse to grain boundaries are actually bound to grain boundary sites, presumably those of high distortion. [1] This cracking, although generally believed to be caused by Nb-rich phases, [1][2][3][4][5] has been also found to be caused by B segregation at grain boundaries.…”

Section: Introductionmentioning

confidence: 99%

“…[6,7] The segregation of B at grain boundaries, in general, occurs by two mechanisms-equilibrium segregation [8,9] and nonequilibrium segregation. [10][11][12][13][14][15] The concentration of complexes, C c , at temperature T is given by The amount of this segregation increases with decreasing annealing temperature and increasing solute concentration in the matrix.…”

Section: Introductionmentioning

confidence: 99%

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Grain boundary segregation of boron in INCONEL 718

Chen

Chaturvedi

Richards³

et al. 1998

Metall Mater Trans A

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The segregation behavior of boron at grain boundaries in two INCONEL 718 + based alloys with different B concentrations was studied. The alloys, one containing 11 ppm of B and the other 43 ppm, were homogenized at 1200 ЊC for 2 hours followed by water quenching and air cooling. A strong segregation of boron at grain boundaries was observed using secondary ion mass spectrometry after the heat treatment in both the alloys. The segregation was found mainly to be of nonequilibrium type. The homogenized samples were also annealed at 1050 ЊC for various lengths of time. During annealing, boride particles were observed to first form at grain boundaries and then to dissolve on continued annealing at 1050 ЊC. The mechanisms of segregation and desegregation of B are discussed.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Grain boundary segregation of boron in INCONEL 718

Chen

Chaturvedi

Richards³

et al. 1998

Metall Mater Trans A

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“…This suggests that B GB increases as austenitizing temperature rises, which can not be explained by equilibrium segregation mechanism. X. Tingdong et al 12) and X. L. He et al 13) reported that segregation on grain boundaries of B increases with increasing heating temperature at a low cooling rate but decreases at a high cooling rate because non equilibrium segregation tends to occur during cooling at a low cooling rate. X. Tingdong et al 11) referred 50°C/s as a slow cooling rate.…”

Section: Discussionmentioning

confidence: 99%

Effects of Mo Addition and Austenitizing Temperature on Hardenability of Low Alloy B-added Steels.

Asahi

2002

ISIJ International

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The hardenability change by an addition of B to 0.15%C-Ti added steel was investigated considering the effect of Mo in order to understand one of the peculiar characteristics that austenitizing at higher temperatures reduces the hardenability effect of B. Hardenability monotonically increases with increasing B content up to the optimum B content without the effect of Mo. The optimum B content increases with increasing Mo; 6 ppm, 9 ppm, 13 ppm for 0 % Mo, 0.25 % Mo, 0.50 % Mo. The addition of Mo retards the precipitation of M 23 (CB) 6 and thus more B in solution that contributes to hardenability can exist along grain boundaries by Mo. The optimum B content is reduced with increasing temperatures because much more B concentrates along grain boundaries through non-equilibrium segregation mechanism during cooling from an elevated temperature and thus precipitation of M 23 (CB) 6 easily occurs.

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“…[5] When material to depend on the starting temperature, cooling rate, and bulk was found not to contain grain-boundary precipitates, a susconcentration of solutes. [12][13][14][15][16][17][18][19] ceptibility to HAZ liquation cracking still existed. Borland, [9] The segregation of impurities can also take place during for example, in 1960, suggested that segregation of elements the welding process.…”

Section: Introductionmentioning

confidence: 99%

“…The original theory of liquation it can occur by two mechanisms, viz., equilibrium segregacracking was related to the formation of grain-boundary tion [11] and nonequilibrium segregation. [12][13][14][15][16][17][18][19] In equilibrium liquid through the constitutional liquation of grain-boundary segregation, solute atoms that diffuse to grain boundaries precipitates and the inability of the liquid films to support are actually bound to grain-boundary sites. The extent of the tensile stress developed during cooling after weldthis segregation increases with decreasing temperature and ing.…”

Section: Introductionmentioning

confidence: 99%

Effect of boron segregation at grain boundaries on heat-affected zone cracking in wrought INCONEL 718

Chen

Chaturvedi

Richards

2001

Metall Mater Trans A

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Susceptibility to heat-affected zone (HAZ) cracking during electron-beam welding was studied in two INCONEL 718-based alloys doped with different levels of boron. By lowering the carbon, sulfur, and phosphorous concentrations to be "as low as possible," the occurrence of HAZ cracking was related directly to the level of segregation of boron at grain boundaries, which occurred by nonequilibrium segregation during a preweld heat treatment. The study has demonstrated a direct correlation between the amount of boron segregated at grain boundaries and their susceptibility to HAZ cracking, in terms of the total crack length and number of cracks observed in the HAZ. The analysis of results suggests that both the melting and resolidification temperatures of the boron-segregated grain boundaries can be about 100 ЊC to 200 ЊC lower than those of the grain boundaries that were susceptible to constitutional liquation of Nb carbides on them, making boron more deleterious in causing HAZ cracking.

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Two types of boron segregation at austenite grain boundaries and their mutual relation

Cited by 18 publications

References 5 publications

Grain boundary segregation of boron in INCONEL 718

Grain boundary segregation of boron in INCONEL 718

Effects of Mo Addition and Austenitizing Temperature on Hardenability of Low Alloy B-added Steels.

Effect of boron segregation at grain boundaries on heat-affected zone cracking in wrought INCONEL 718

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