Influence of grain boundaries on the behaviour of carbon and nitrogen in α-iron

Lagerberg, G.; Josefsson, Ake

doi:10.1016/0001-6160(55)90058-4

Cited by 55 publications

(3 citation statements)

References 5 publications

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“…On the other hand, it is known that nitrogen has less tendency to cause grain boundary segregation in steel, as compared to carbon. [20][21][22] This agrees well with the experimental results that k y is hardly influenced by nitrogen. The enlarged k y by nitrogen mentioned above might be due to the large amount of solute nitrogen in austenite matrix leading to the high concentration of nitrogen at grain boundary even though the segregation coefficient is small.…”

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confidence: 87%

Effect of Interstitial Elements on Hall–Petch Coefficient of Ferritic Iron

et al. 2008

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Here, on the assumption that the classical grain boundary segregation theory would be applied to the case of this study, namely, carbon in ferritic steel, the Hall-Petch coefficient was compared with the concentration of carbon at grain boundary. According to the MacLean's theory, 17) solute carbon concentration segregated at ferrite grain boundary at 973 K is calculated by following equation:In this equation, [at%C], Q and R are the total carbon concentration in solid solution, the activation energy of carbon for grain boundary segregation and the gas constant, respectively. As for the value of Q, 78 kJ/mol estimated by Grabke 18) was taken. Figure 6 shows relationship between k y and segregated carbon content calculated by Eq. (3). k y value tends to increase linearly with increasing segregated carbon content, which suggests that grain boundary segregation of interstitial alloy elements significantly prevents the yielding of ferritic steel. Only 60 ppm carbon causes marked grain boundary segregation to 80 at%, resulting in the enlargement of the k y from 100 (in IF-steel) to 550 MPa · mm 1/2 . The solubility of carbon was reported to be approximately 60 ppm even at ambient temperature 19) in Fe-C binary alloy. Therefore, it could be understood that the similar k y values, around 600 MPa · mm 1/2 , have been reported in lots of previous studies on grain refinement strengthening of ferritic steels except for IF-steels. On the other hand, it is known that nitrogen has less tendency to cause grain boundary segregation in steel, as compared to carbon. [20][21][22] This agrees well with the experimental results that k y is hardly influenced by nitrogen. The enlarged k y by nitrogen mentioned above might be due to the large amount of solute nitrogen in austenite matrix leading to the high concentration of nitrogen at grain boundary even though the segregation coefficient is small. Conclusions(1) IF-steel has a low Hall-Petch coefficient of approximately 100 MPa · mm 1/2 . The Hall-Petch coefficient of ferritic iron monotonously increases with increasing solute carbon content, and it levels off at 550-600 MPa · mm 1/2 when the solute carbon content reaches 60 ppm. On the other hand, the solute nitrogen hardly affects the Hall-Petch coefficient.(2) The increase in Hall-Petch coefficient by solute carbon seems to be derived from the grain boundary segregation of carbon atoms. The small effect of solute nitrogen on Hall-Petch coefficient could be explained by the less tendency of nitrogen atoms to cause grain boundary segregation. ISIJ, Tokyo, Japan, (1991), 762. 12) V. G. Gavriljuk, H. Berns, C. Escher, N. I. Glavatskaya, A. Sozinov and Yu. N. Petrov: Mater. Sci. Forum, 318-320 (1999)

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confidence: 87%

Effect of Interstitial Elements on Hall–Petch Coefficient of Ferritic Iron

et al. 2008

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“…These α‐islands are extremely small and too scarce to affect the fatigue life. Carbon atoms have a strong affinity to grain and sub‐boundaries in austenite and ferrite 22, 23. It can be concluded from the present results that they are preferentially segregated at stacking faults which are prerequisites for the formation of ε ‐plates in the deformed austenite.…”

Section: Discussionmentioning

confidence: 54%

“…It can be concluded from the present results that they are preferentially segregated at stacking faults which are prerequisites for the formation of ε ‐plates in the deformed austenite. In contrast, nitrogen atoms tend to segregate much less 22–24. However, they are more able to form clouds around dislocations, because of larger elastic distortions of the austenite 3, 25.…”

Section: Discussionmentioning

confidence: 99%

Fatigue and Structural Changes of High Interstitial Stainless Austenitic Steels

Berns

Gavriljuk

Nabiran

et al. 2010

steel research int.

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Steels with 18 to 19 mass% Cr and Mn each were studied in the as-cast condition containing 0.85 mass% C þ N and in the elektro-slag-remelted and hot worked condition containing 0.96 mass% C þ N after final solution annealing. The latter was also tested after 20% prestraining. The results of tensile tests were compared to those of rotating bending and push/pull loading. The higher C þ N content raised the 0.2% proof strength to about 600 MPa of which 70% were retained as fatigue limit of rotating bending at 10 7 cycles and a failure probability of 50%. Prestraining further improved this limit but lowered it in relation to the proof strength. The structural components of cold work hardening under unidirectional loading and cyclic loading were similar (planar slip, dislocation, twins and e-martensite) except for precipitates in the latter. Nitrides appeared in the austenite and carbides in the e-plates.

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Internal Friction

Fast¹

1976

Gases in Metals

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Influence of grain boundaries on the behaviour of carbon and nitrogen in α-iron

Cited by 55 publications

References 5 publications

Effect of Interstitial Elements on Hall–Petch Coefficient of Ferritic Iron

Effect of Interstitial Elements on Hall–Petch Coefficient of Ferritic Iron

Fatigue and Structural Changes of High Interstitial Stainless Austenitic Steels

Internal Friction

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