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Study of the effect of nano-sized precipitates on the mechanical properties of boron-added low-carbon steels by neutron scattering techniques.

Seong BS, Cho YR, Shin EJ, Kim SI, Choi SH, Kim HR, Kim YJ - J Appl Crystallogr (2008)

Bottom Line: In the BA steels, the number of boron precipitates, such as BN, Fe(3)(C,B) and MnS, surrounded by BN layers increased drastically at higher hot-rolling temperatures.The volume fraction of the fine precipitates of the BA steels was higher than that of the BF steels; this difference is related to the rapid growth of the BN layers on the MnS and CuS precipitates.Boron addition to low-carbon steels resulted in a reduction in strength and an improvement in elongation; this behaviour is related to the reduction of the solute carbon and the nitrogen contents in the ferrite matrix caused by the precipitation of BN, as well by the increase in the volume fraction of the cementites.

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ABSTRACT
Small-angle neutron scattering (SANS) and neutron powder diffraction (ND) techniques were used to study quantitatively the effect of nano-sized precipitates and boron addition on the mechanical properties of low-carbon steels. SANS was used to evaluate nano-sized precipitates, smaller than about 600 A in diameter, and ND was used to determine the weight fraction of the cementite precipitates. Fine core-shell structured spherical precipitates with an average radius of ~50 A, such as MnS and/or CuS, surrounded by BN layers were observed in the boron-added (BA) low-carbon steels; fine spherical precipitates with an average radius of ~48 A were mainly observed in the boron-free (BF) low-carbon steels. In the BA steels, the number of boron precipitates, such as BN, Fe(3)(C,B) and MnS, surrounded by BN layers increased drastically at higher hot-rolling temperatures. The volume fraction of the fine precipitates of the BA steels was higher than that of the BF steels; this difference is related to the rapid growth of the BN layers on the MnS and CuS precipitates. Boron addition to low-carbon steels resulted in a reduction in strength and an improvement in elongation; this behaviour is related to the reduction of the solute carbon and the nitrogen contents in the ferrite matrix caused by the precipitation of BN, as well by the increase in the volume fraction of the cementites.

No MeSH data available.


Nuclear scattering cross sections (open squares) and nuclear plus magnetic scattering cross sections (open circles) for (a) BA, FET 1151 K and (b) BF, FET 1148 K samples.
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fig3: Nuclear scattering cross sections (open squares) and nuclear plus magnetic scattering cross sections (open circles) for (a) BA, FET 1151 K and (b) BF, FET 1148 K samples.

Mentions: Fig. 2 ▶ shows an example of the two-dimensional SANS spectra obtained with a magnetic field of 1.0 T for the BA and BF steels. It is seen that the patterns in both samples are isotropic. In order to investigate the effect of magnetic scattering on the SANS patterns, the nuclear scattering contributions (open squares) extracted from the two-dimensional SANS patterns are compared with nuclear plus magnetic scattering contributions (open circles), as shown in Fig. 3 ▶. In both the BA and the BF steels, the magnetic scattering is not strong over all the Q ranges, and the contributions from the magnetic scattering can be negligible in the range Q > 0.03 Å−1, corresponding to a precipitate size of < 200 Å.


Study of the effect of nano-sized precipitates on the mechanical properties of boron-added low-carbon steels by neutron scattering techniques.

Seong BS, Cho YR, Shin EJ, Kim SI, Choi SH, Kim HR, Kim YJ - J Appl Crystallogr (2008)

Nuclear scattering cross sections (open squares) and nuclear plus magnetic scattering cross sections (open circles) for (a) BA, FET 1151 K and (b) BF, FET 1148 K samples.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2553556&req=5

fig3: Nuclear scattering cross sections (open squares) and nuclear plus magnetic scattering cross sections (open circles) for (a) BA, FET 1151 K and (b) BF, FET 1148 K samples.
Mentions: Fig. 2 ▶ shows an example of the two-dimensional SANS spectra obtained with a magnetic field of 1.0 T for the BA and BF steels. It is seen that the patterns in both samples are isotropic. In order to investigate the effect of magnetic scattering on the SANS patterns, the nuclear scattering contributions (open squares) extracted from the two-dimensional SANS patterns are compared with nuclear plus magnetic scattering contributions (open circles), as shown in Fig. 3 ▶. In both the BA and the BF steels, the magnetic scattering is not strong over all the Q ranges, and the contributions from the magnetic scattering can be negligible in the range Q > 0.03 Å−1, corresponding to a precipitate size of < 200 Å.

Bottom Line: In the BA steels, the number of boron precipitates, such as BN, Fe(3)(C,B) and MnS, surrounded by BN layers increased drastically at higher hot-rolling temperatures.The volume fraction of the fine precipitates of the BA steels was higher than that of the BF steels; this difference is related to the rapid growth of the BN layers on the MnS and CuS precipitates.Boron addition to low-carbon steels resulted in a reduction in strength and an improvement in elongation; this behaviour is related to the reduction of the solute carbon and the nitrogen contents in the ferrite matrix caused by the precipitation of BN, as well by the increase in the volume fraction of the cementites.

View Article: PubMed Central - HTML - PubMed

ABSTRACT
Small-angle neutron scattering (SANS) and neutron powder diffraction (ND) techniques were used to study quantitatively the effect of nano-sized precipitates and boron addition on the mechanical properties of low-carbon steels. SANS was used to evaluate nano-sized precipitates, smaller than about 600 A in diameter, and ND was used to determine the weight fraction of the cementite precipitates. Fine core-shell structured spherical precipitates with an average radius of ~50 A, such as MnS and/or CuS, surrounded by BN layers were observed in the boron-added (BA) low-carbon steels; fine spherical precipitates with an average radius of ~48 A were mainly observed in the boron-free (BF) low-carbon steels. In the BA steels, the number of boron precipitates, such as BN, Fe(3)(C,B) and MnS, surrounded by BN layers increased drastically at higher hot-rolling temperatures. The volume fraction of the fine precipitates of the BA steels was higher than that of the BF steels; this difference is related to the rapid growth of the BN layers on the MnS and CuS precipitates. Boron addition to low-carbon steels resulted in a reduction in strength and an improvement in elongation; this behaviour is related to the reduction of the solute carbon and the nitrogen contents in the ferrite matrix caused by the precipitation of BN, as well by the increase in the volume fraction of the cementites.

No MeSH data available.