Influence of sulphur and niobium on hot ductility of as cast steels

Abushosha, R.; Vipond, R.; Mintz, B.

doi:10.1179/026708391790182962

Cited by 10 publications

(14 citation statements)

References 5 publications

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“…Fracture surfaces obtained from specimens tested in the singlephase austenite region exhibited intergranular decohesion, displaying flat, featureless facets, indicating failure due to grain boundary sliding. [9,12] An example of such a failure is shown in Figure 5(b). Large, deep voids were observed in specimens that displayed high ductility (not shown).…”

Section: Figures 2(a) Through (C)mentioning

confidence: 96%

Hot Ductility of Nb- and Ti-Bearing Microalloyed Steels and the Influence of Thermal History

Carpenter

Dippenaar

Killmore³

2009

Metall Mater Trans A

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The hot ductility of Nb, Ti, and Nb-Ti containing steels has been studied under direct-cast conditions. A Gleeble 3500 thermomechanical simulator was used to determine hot ductility over the temperature range 1100°C to 700°C at a low strain rate of 7.5 9 10 À4 s À1 . Tensile samples were cooled at two different cooling rates, 100°C/min and 200°C/min, simulating, respectively, thick and thin slab casting processes. Complex thermal patterns designed to simulate the cooling conditions experienced near the surface of a slab during continuous casting were carried out for the Nb-Ti steel. The Nb-Ti steel had lower ductility than both the Nb and Ti steels. Increasing the cooling rate generally deteriorated ductility. The low recovery of ductility at higher temperatures is explained in terms of a low strain rate and fine precipitation delaying the onset of dynamic recrystallization. This can promote intergranular cracking as a result of grain boundary sliding in the austenite. At lower temperatures, ductility was further reduced due to the formation of thin ferrite films at the prior austenite grain boundaries. Simulating the thermal history experienced near the surface of thin (90 mm) cast slab improved ductility of the Nb-Ti steel by promoting coarser NbTi(C,N). This exposes a potential flaw in a simplified hot-ductility test: a failure to accurately represent the influence of the thermomechanical schedule on precipitation and, hence, hot ductility.

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Section: Figures 2(a) Through (C)mentioning

confidence: 96%

Hot Ductility of Nb- and Ti-Bearing Microalloyed Steels and the Influence of Thermal History

Carpenter

Dippenaar

Killmore³

2009

Metall Mater Trans A

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“…The reasons for the decrease of hot ductility have been studied by many scholars. [3][4][5][6][7][8][9][10][11][12][13][14][15][38][39][40][41][42] Zhang et al indicated that hot ductility trough resulted from the formation of pro-eutectoid ferrite films along prior austenite grain boundaries. [38,39] The distribution of the impurities [40] or precipitation [39,41] containing Ti, Nb, B, etc.…”

Section: A Factors Influencing the Hot Ductilitymentioning

confidence: 99%

“…It was reported that the formations of pro-eutectoid ferrite film and the precipitation of V, Nb, or Al at austenite grain boundaries play important roles in the loss of hot ductility. [3][4][5][6] Mintz et al [7] found that reducing the C (lower than the peritectic C range) and N levels brings better ductility in Nb-containing steels because it limits the amount of Nb(CN) precipitation. Kyung Chul Cho [8] researched the effects of Nb and Ti addition on hot ductility of boron-bearing steel and found that a small amount of addition of Ti obviously improved the hot ductility of B-Nb steel.…”

Section: Introductionmentioning

confidence: 98%

“…These data can be obtained using specific process parameters corresponding to the actual production-line parameters. [4,16] In order to establish suitable schedule to prevent the slab surface from cracking, hot ductility behavior should be investigated, especially for the novel steels. [17,18] Continuous rolling (CR) is a very important step after CC in the production procedure of steels.…”

Section: Introductionmentioning

confidence: 99%

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Hot Ductility and Compression Deformation Behavior of TRIP980 at Elevated Temperatures

Zhang

Gan

et al. 2017

Metall Mater Trans B

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The hot ductility tests of a kind of 980 MPa class Fe-0.31C (wt pct) TRIP steel (TRIP980) with the addition of Ti/V/Nb were conducted on a Gleeble-3500 thermomechanical simulator in the temperatures ranging from 873 K to 1573 K (600°C to 1300°C) at a constant strain rate of 0.001 s À1 . It is found that the hot ductility trough ranges from 873 K to 1123 K (600°C to 850°C). The recommended straightening temperatures are from 1173 K to 1523 K (900°C to 1250°C). The isothermal hot compression deformation behavior was also studied by means of Gleeble-3500 in the temperatures ranging from 1173 K to 1373 K (900°C to 1100°C) at strain rates ranging from 0.01 s À1 to 10 s À1 . The results show that the peak stress decreases with the increasing temperature and the decreasing strain rate. The deformation activation energy of the test steel is 436.7 kJ/mol. The hot deformation equation of the steel has been established, and the processing maps have been developed on the basis of experimental data and the principle of dynamic materials model (DMM). By analyzing the processing maps of strains of 0.5, 0.7, and 0.9, it is found that dynamic recrystallization occurs in the peak power dissipation efficiency domain, which is the optimal area of hot working. Finally, the factors influencing hot ductility and thermal activation energy of the test steel were investigated by means of microscopic analysis. It indicates that the additional microalloying elements play important roles both in the loss of hot ductility and in the enormous increase of deformation activation energy for the TRIP980 steel.

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“…However, this may cause deterioration of the steel properties due to the increased levels of undesirable elements, such as S, Sb, Sn, As, P, Cu, and others. [1,2,3] Most of these elements can be controlled in steel making processes, but it is difficult to remove tin and copper using present techniques. As a consequence, their concentrations could be higher in the recycled steel than in the original one.…”

Section: Introductionmentioning

confidence: 99%

The role of tin in the hot-ductility deterioration of a low-carbon steel

Song

Zhou

Jia

et al. 2003

Metall Mater Trans A

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The effect of tin on the hot ductility of a 0.15 wt pct C steel is investigated using a continuous-casting thermal simulator with three cooling rates: 5°C/s, 10°C/s, and 20°C/s. Non equilibrium grain-boundary segregation of tin occurs during cooling and plays an important role in reducing the steel hot ductility. There is a critical cooling rate for the Sn segregation being between 5°C/s and 20°C/s. When the cooling rate is higher than the critical cooling rate, the segregation caused by diffusion of tin-vacancy complexes to the boundary is dominant, leading the boundary concentration of tin to increase with decreasing cooling rate. However, when the cooling rate is lower than the critical cooling rate, the desegregation caused by backward diffusion of tin away from the boundary also takes place during cooling, leading the boundary concentration of tin to decrease with decreasing cooling rate.

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Influence of sulphur and niobium on hot ductility of as cast steels

Cited by 10 publications

References 5 publications

Hot Ductility of Nb- and Ti-Bearing Microalloyed Steels and the Influence of Thermal History

Hot Ductility of Nb- and Ti-Bearing Microalloyed Steels and the Influence of Thermal History

Hot Ductility and Compression Deformation Behavior of TRIP980 at Elevated Temperatures

The role of tin in the hot-ductility deterioration of a low-carbon steel

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