Effect of Thermal Cycle and Nitrogen Content on the Hot Ductility of Boron-bearing Steel

Cho, Kyung Chul; Mun, Dong Jun; Kang, Myung Ho; Lee, Jae Sang; Park, Joong Kil; Koo, Yang Mo

doi:10.2355/isijinternational.50.839

Cited by 27 publications

(18 citation statements)

References 20 publications

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“…With high N content; BN precipitates were randomly distributed in the interior of the prior austenite and preferentially at austenite grain boundaries, whereas, the precipitates were rather sparsely distributed and larger in the B-bearing steel of low N content as shown Fig.2.60 [147]. Fig.2.58 The effect of an addition of B on the hot ductility of C steels in thermal cycles (A) [147].…”

Section: Boronmentioning

confidence: 98%

“…Recently, the effect of boron precipitation behavior on the hot ductility of B containing steel was investigated by Cho et al [146,147]. The hot ductility of the B containing steel was found to be sensitive to the cooling rate in the range of 1 to 20 o C/s, whereas that of B-free steel showed little change with cooling rate.…”

Section: Boronmentioning

confidence: 99%

“…The hot ductility of a B-bearing steel was investigated by hot tensile tests under two types of thermal cycles; (a) direct cooled to straining temperatures and (b) under-cooled and reheated to the straining temperatures. The effect of N content on the hot ductility of Bbearing steel was also investigated [147]. Addition of B to plain carbon steel deteriorated hot ductility under the thermal cycle which introduced direct fast cooling to straining temperature ( Fig.2.58) because of the precipitation of BN in the lower temperature region of the γ single phase.…”

Section: Boronmentioning

confidence: 99%

“…These can be summarised as follows: 1) The cooling rate should be 6~100 o C/min, the lower cooling rate being preferred [147,175,177,179]. 2) S levels must be kept low to reduce the volume fraction of MnS.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Hot ductility of TWIP steels

Kang

Tuling

Banerjee

et al. 2011

Materials Science and Technology

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The hot ductility of twin induced plasticity (TWIP), 0·6 wt-C steels containing 18–22 wt-Mn with N levels in the range 0·005–0·023 wt- and the Al additions either low (<0·05 wt-) or high (1·5 wt-) has been examined. Little change in ductility occurred in the temperature range 1100–650°C as the structure was always fully austenitic. Ductility was generally poor (<40), reduction of area values, the best ductility at the higher Al level being given by the steel with the lowest N and S levels. Because the steel is fully austenitic, the ductility is solely dependent on that for unrecrystallised austenite. Therefore, to avoid transverse cracking the volume of second phase particles should be kept to a minimum, i.e. the N should be low to reduce the amount of AlN that can be precipitated out and the S level should be as low as possible to limit the amount of MnS inclusions. Metallographic and TEM studies were carried out and the poor ductility was found to be due to extensive precipitation of AlN at the austenite grain boundaries. Increasing the cooling rate from the melting point to the test temperature from 60 to 180°C min−1 or introducing an undercooling step both led to even worse ductility.

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Section: Boronmentioning

confidence: 98%

Section: Boronmentioning

confidence: 99%

Section: Boronmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Hot ductility of TWIP steels

Kang

Tuling

Banerjee

et al. 2011

Materials Science and Technology

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“…Kim 12) demonstrated that the percipitation of Fe 23 (C,B) 6 decreased ferrite at austenite grain boundaries which leads to hot ductility improvement. Cho et al 14) commented that fine BN particles would form in boroncontaining slabs which cooled down with high cooling rate, the formation of fine BN results in the decrease of hot ductility. Generally, the purpose of titanium addition in boron-containing steels is for protecting the effect of boron.…”

Section: Introductionmentioning

confidence: 99%

Influence of Boron Addition on the Hot Ductility of Low-Carbon Aluminum-Killed Steel

Liu

Shi

et al. 2015

Mater. Trans.

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The hot ductility of low-carbon aluminum-killed steel with different boron contents was investigated. The hot tensile experiment was conducted using Gleeble3500 simulator. The reduction of area of each specimen was determined to estimate the quality of hot ductility. The changes of precipitates in studied steel were calculated by Thermo-Calc software. The microstructures of specimens were observed using optical microscopy (OM), sanning electron microscopy (SEM) and transmission electron microscopy (TEM). Based on the experimental results, the fracture types of specimens were analyzed. The results show that the hot ductility improves with increase in boron content. In the experimental condition of this study, the combining ability of boron with nitrogen is greater than that aluminum and nitrogen in the energetics point of view. Coarse BN particles decrease the effect of pinning grain boundary by fine AlN. Boron in solid solution plays a role of inhibiting the austenite/ ferrite transformation. The improvement of hot ductility is caused by the formation of coarse BN and existence of boron in solid solution.

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Hot Ductility and Fracture Phenomena of Low‐Carbon V–N–Cr Microalloyed Steels

Liu

et al. 2019

steel research int.

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The hot ductility of low‐carbon V–N–Cr microalloyed steel is studied using a thermomechanical simulator. The steel is solution treated at 1350 °C and cooled at 15 °C s−1 to the test temperature in the range of 650–1200 °C. Next, they are strained to failure at a strain rate of 4 × 10−3 or 4 × 10−2 s−1, and ductility troughs are obtained. The results reveal a ductility trough in V–N–Cr steels in the range of 650–900 °C with a minimum reduction in area (RA) value of 13.5 % at 800 °C and strain rate of 4 × 10−3 s−1. The occurrence of dynamic recrystallization from 950 to 1200 °C has a substantial contribution to high ductility and on the formation of film‐like ferrite at prior austenite grain boundaries. The fracture mechanism changes from intergranular to highly ductile microvoid coalescence in the temperature range of 800–1200 °C and at a higher strain rate. Ductility loss in the V–N–Cr steel is caused by the presence of a high density of VN and/or V(C,N) precipitates, which are linearly present within the matrix, and a small number of random precipitates are present at the boundary.

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Effect of Thermal Cycle and Nitrogen Content on the Hot Ductility of Boron-bearing Steel

Cited by 27 publications

References 20 publications

Hot ductility of TWIP steels

Hot ductility of TWIP steels

Influence of Boron Addition on the Hot Ductility of Low-Carbon Aluminum-Killed Steel

Hot Ductility and Fracture Phenomena of Low‐Carbon V–N–Cr Microalloyed Steels

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