The Influence of Ti on the Hot Ductility of Nb-bearing Steels in Simulated Continuous Casting Process.

Luo, Haiwen; Karjalainen, L.P.; Porter, David; Liimatainen, Heidi-Marja; Zhang, Yan

doi:10.2355/isijinternational.42.273

Cited by 35 publications

(46 citation statements)

References 15 publications

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“…Hot tensile testing of in situ melted samples, led to a large volume fraction of fine strain induced precipitates at temperatures as high as 1000 o C seriously impairing ductility as shown Fig.2.65 [150]. An increase in the Ti level led to even worse ductility.…”

Section: Titaniummentioning

confidence: 99%

“…Commercially, for low nitrogen steels (0.005%N), titanium levels are recommended to be 2~4 times the nitrogen level, although Turkdogan [68] has stated that the favoured ratio is 4. In contrast, when laboratory hot tensile tests are carried out, it is found that small additions of titanium lead to poor ductility [78,131,150], unless the cooling rate after casting is slow [79]. When simulated cooling rates are fast, as for thin slab casting, precipitation is always fine.…”

Section: Titaniummentioning

confidence: 99%

“…Luo et al [150] have examined the influence of Ti/N ratio on the hot ductility of a higher C, 0.1C, 1.4%Mn, 0.03%Nb, low N (0.005%) steel having Ti/N ratios of 0 to 6.4. Hot tensile testing of in situ melted samples, led to a large volume fraction of fine strain induced precipitates at temperatures as high as 1000 o C seriously impairing ductility as shown Fig.2.65 [150].…”

Section: Titaniummentioning

confidence: 99%

See 2 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: Titaniummentioning

confidence: 99%

Section: Titaniummentioning

confidence: 99%

Section: Titaniummentioning

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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“…10, the formation of these particles may be likely that TiN parties precipitat firstly and then become the nucleation sites of precipitates containing Nb when the deformation occurs. 20) In addition, the formation of these particles may also be likely due to a combination of Nb(C, N) and Ti(C, N) which precipitate in the meantime in the process of deformation. 21) However, these particles are rarely found in lower temperature range.…”

Section: Thickness Of Ferrite Filmsmentioning

confidence: 99%

Effect of the Induced Ferrite and Precipitates of Nb–Ti Bearing Steel on the Ductility of Continuous Casting Slab

2014

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The hot ductility of Nb-Ti bearing ship plate steel has been obtained using the Gleeble 1 500 thermalmechanical simulator, the results showed that the ductility trough of the reduction of area (R.A) curve of Nb-Ti bearing ship plate steel is wider than other steels without Nb. In order to investigate the reasons of the loss of the ductility, a series of studies have been done. It was found that Nb(C,N) particles with a mean size of 9 nm precipitate at 950°C and induce the formation of the nuclei of grain boundary ferrite, which could lead to strain concentration at grain boundaries as well as the poor uniformity of ferrite films thickness. This causes rapid decrease of the R.A values with the temperature cooling from 1 000 to 950°C. When the temperature falls to 900°C, a large number of Nb(C,N) particles precipitate, which promote further formation of the grain boundary ferrite films. Therefore, the thickness of ferrite films formed at different time makes a difference and presents a poor uniformity. As the temperature down to 850°C, hot ductility further reduces because of the worse uniformity of ferrite films thickness which leads to strain concentration at the grain boundary. When temperature is close to Ae3 (816°C), the formation and growth of ferrite films become faster due to austenite-ferrite phase transformation, which leads to the uniformity of ferrite film thickness at worst, so that the R.A value exhibits a rapid decrease. After the temperature is lower than Ae3, ferrite films are markedly thickened, which compensate parts of adverse effects from the poor uniformity of ferrite films thickness and reduce the strain concentration at grain boundaries. In this way, ductility begins to recover.

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“…[12][13][14][15][16] A relatively large number of papers available in literature refers to as cast steels tested by cooling at various rates from the melting temperature or by reheating the cast structure from room temperature. 1,2,[6][7][8][9]12,13,[17][18][19][20] Under these conditions, the coarse grain structure and the segregation of alloying elements at boundaries strongly affects precipitation. On the contrary, less attention has been paid to hot ductility of wrought steels.…”

Section: Introductionmentioning

confidence: 99%