On the mechanism of liquid copper penetration into iron grain boundaries

Fredriksson, Hasse; Hansson, Karin; Olsson, Anna-Karin

doi:10.1034/j.1600-0692.2001.d01-36.x

Cited by 41 publications

(19 citation statements)

References 6 publications

(11 reference statements)

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“…The quantification of the amount of liquid phase for the 0.06 Sn alloy with or without annealing in N 2 , however, does not vary much, as shown in Figure 11, suggesting that the back-diffusion flux was indeed negligible for the time period in current experiments. Calculations based on the formulas in Fredriksson et al's article [52] with the interface concentrations in the current experiment assuming a binary diffusion process (either Cu or Sn play the major role) resulted in a much smaller width (~0.05 lm) and length (~50 lm) of the cracks than the experimental observation (Figures 6(b) and (c)). Moreover, no porosity was observed at the liquid-cFe interface in the grain boundary in the FIB results (Figure 7(b)).…”

Section: Condensation Of Vacancymentioning

confidence: 82%

“…[51] Fredriksson et al [52] proposed that although liquid Cu diffused to cFe grain boundaries, the lateral diffusion of Cu through the grain boundaries could cause vacancies condensation, which was responsible for the propagation and broadening of the liquid layer in the grain boundaries. Although the impurity diffusivity of Sn in matrix Fe (2.10 9 10 À14 m 2 /s) is much faster than the selfdiffusivity of Fe (1.56 9 10 À15 m 2 /s) and the impurity diffusivity of Cu (2.66 9 10 À15 m 2 /s), [30] the interface concentration of Sn at the cFe side was expected to be small as shown in Figure 9(c), and therefore, the resulting back-diffusion flux of Sn is consequently small.…”

Section: Condensation Of Vacancymentioning

confidence: 99%

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Effects of Small Additions of Tin on High-Temperature Oxidation of Fe-Cu-Sn Alloys for Surface Hot Shortness

Yin

Sridhar

2010

Metall Mater Trans B

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Steel produced in an electric arc furnace contains a high amount of copper (Cu) that causes a surface-cracking phenomenon called surface hot shortness. It is known that tin (Sn) can exacerbate the hot shortness problem. A series of iron (Fe)-0.3 wt pct Cu-x wt pct Sn alloys with an Sn content ranging from 0.03 to 0.15 wt pct was oxidized in air at 1423 K (1150°C) for 60 seconds, 300 seconds, and 600 seconds using thermogravimetry. A numerical model developed in a previous article was applied to predict the liquid-cFe interface concentrations and interface morphology in the Fe-Cu-Sn ternary system. Scanning electron microscopy investigations show that (1) The interface between the oxide and the metal is planar as predicted by the numerical model, (2) Sn leads to severe Cu-rich liquid penetration and cracking along the grain boundaries, and (3) open cracks with Fe oxides were found beneath the oxide-metal interface. The focused ion beam serial-sectioning technique was used to reveal a three-dimensional structure of cracks in the grain boundary containing Cu-rich liquid and Fe oxides.

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Section: Condensation Of Vacancymentioning

confidence: 82%

Section: Condensation Of Vacancymentioning

confidence: 99%

Effects of Small Additions of Tin on High-Temperature Oxidation of Fe-Cu-Sn Alloys for Surface Hot Shortness

Yin

Sridhar

2010

Metall Mater Trans B

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“…Swelling of Fe-Cu compacts during sintering at temperatures above the melting point of copper has been extensively studied during the past four decades [1][2][3][4][5]. The swelling mechanism accepted today is that liquid copper penetrates into iron interparticle boundaries, and leads to the swelling.…”

Section: Introductionmentioning

confidence: 99%

Modelling of swelling of Fe–Cu compacts sintered at temperatures above the copper melting point

Zhang

Sandström

Wang

2004

Journal of Materials Processing Technology

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“…The rate of penetration of Cu is very slow when tensile stress does not exist. 13) But under tensile stress, the penetration proceeds at a much higher rate. McLean 14) proposed the following critical condition that the stress starts crack propagation by liquid embrittlement.…”

Section: Effects Of Elements On Microstructure Near Steel/scale Intermentioning

confidence: 99%

Suppression of Surface Hot Shortness due to Cu in Recycled Steels

et al. 2002

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The most serious problem in the recycling of steel is the occurrence of surface hot shortness during hot deformation due to the mixing of Cu from scrap into steels. Tin accelerates the effect of Cu. The surface hot shortness is caused by liquid embrittlement, that is, formation of the liquid Cu-enriched phase through preferential oxidation of Fe atoms at the steel/scale interface during heating for hot deformation and penetration of this Cu-enriched phase into the grain boundaries. Decrease in the amount of the liquid Cu-enriched phase penetrating into grain boundaries can suppress the surface hot shortness. The amount of the liquid Cu-enriched phase penetrating into the grain boundaries can be reduced by the suppression of oxidation, occlusion of the Cu-enriched phase into the scale, back-diffusion of Cu into the steel matrix and suppression of penetration of the liquid Cu-enriched phase. Therefore, the effects of various elements and conditions of heating and deformation on the surface hot shortness, oxidation, amount of the Cu-enriched phase at the interface and the penetration were examined by tensile tests at high temperatures, thermogravimetry and optical microscopy. The conclusion can be summarized as follows. Silicon, Mn, S (+Mn) and B reduce the susceptibility to the surface hot shortness through decreasing the amount of Cu-enriched phase at the steel/scale interface. The effect of Si is significant. Carbon reduces the oxidation rate in LNG combustion gas. Phosphorus, Si, B and C reduce the susceptibility to the surface hot shortness through restraining the penetration of the Cu-enriched phase into grain boundaries. Heating at higher temperatures reduces the susceptibility mainly through a reduction in the amount of the Cu-enriched phase at the steel/scale interface, although the loss of steels by oxidation increases. A large grain size accelerates the surface hot shortness. A small amount of H 2 O in air significantly accelerates the surface hot shortness. Effects of H 2 O in heating atmosphere depend on the steel composition and more detailed research on this is desired. Very slow deformation does not cause liquid embrittlement through dynamical re-crystallization, while at a fast deformation rate the embrittlement is suppressed by an increase in the critical stress for the liquid embrittlement. Multiple methods using physical metallurgy suggested by the present research for suppressing the surface hot shortness should be applied together with other methods through separation, smelting and design of fabrication in order to promote the recycling of steels.

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On the mechanism of liquid copper penetration into iron grain boundaries

Cited by 41 publications

References 6 publications

Effects of Small Additions of Tin on High-Temperature Oxidation of Fe-Cu-Sn Alloys for Surface Hot Shortness

Effects of Small Additions of Tin on High-Temperature Oxidation of Fe-Cu-Sn Alloys for Surface Hot Shortness

Modelling of swelling of Fe–Cu compacts sintered at temperatures above the copper melting point

Suppression of Surface Hot Shortness due to Cu in Recycled Steels

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