Effect of Cooling Rate on ZST, LIT and ZDT of Carbon Steels Near Melting Point.

Won, Young Mok; Kim, Kyung-Hyun; Yeo, Taejung; Oh, Kyu Hwan

doi:10.2355/isijinternational.38.1093

Cited by 74 publications

(67 citation statements)

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“…(4) can give the flow stresses of d-phase and g-phase of carbon steels when those parameters of A, Q, b, m and n are determined for each phase. The critical strain (e c ) for internal crack formation can be expressed as follows, taking the effect of the brittle temperature range (DT B ) and strain rate into account as discussed in literature; 8,13) . (5) where j is constant, m* and n* are the strain rate exponent and the brittle temperature range exponent on the critical strain, respectively.…”

Section: Stress Calculation In Mushy Zonementioning

confidence: 99%

“…Kim et al 1) proposed the brittle temperature range as ZDTՅ DT B ՅLIT and used the solid fraction of 0.9 at LIT as Clyne and others suggested. The LIT and ZDT were taken as the temperatures at which the solid fractions become 0.90 and 0.99, 8) respectively, in this study. The evaluated parameters in Eq.…”

Section: Stress Calculation In Mushy Zonementioning

confidence: 99%

“…With the increase in the cooling rate and the content of solute elements, especially phosphorus and sulfur, the brittle temperature range expands largely due to the severe segregation of solute elements at the final stage of solidification which is influenced by the cooling rate. 8) The fracture stress of solidifying shell was estimated by the submerged split chill tension testing method [16][17][18] at high strain rate range of 10 Ϫ1 -1/sec. The high strain rate was chosen to minimize the shell growth during the testing.…”

Section: Stress Calculation In Mushy Zonementioning

confidence: 99%

“…They reported that the tensile strength of carbon steel was dependent on the phase state and ZST and ZDT corresponding to the solid fraction of about 0.6-0.8 with various carbon contents. Won et al 8) reported that the critical solid fractions at ZST and ZDT corresponded to 0.75 and 0.99, respectively, which were determined by the statistical assessment of experimentally measured data with the microsegregation analysis at various carbon contents and cooling rates. To determine ZST and ZDT in the temperature range of mushy zone by high temperature tensile test, the precise control and evaluation of temperatures corresponding to the mechanical properties are important.…”

Section: Introductionmentioning

confidence: 99%

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Mechanical Behavior of Carbon Steels in the Temperature Range of Mushy Zone.

Seol

Won

et al. 2000

ISIJ International

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Section: Stress Calculation In Mushy Zonementioning

confidence: 99%

Section: Stress Calculation In Mushy Zonementioning

confidence: 99%

Section: Stress Calculation In Mushy Zonementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Mechanical Behavior of Carbon Steels in the Temperature Range of Mushy Zone.

Seol

Won

et al. 2000

ISIJ International

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“…5,16) Cracks can originate from the region where S C exceeds 1 and the possibility of solidification cracking increases with increasing value of S C . In this study, the corresponding solid fraction for LIT abd ZDT were used to be 0.9 and 0.99, which is proposed by Clyen et al 14) and Won et al,27) respectively. …”

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Analysis of Solidification Cracking Using the Specific Crack Susceptibility.

et al. 2000

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Using a 2-dimensional finite element, the effects of carbon content, slab width, narrow face taper and casting speed on solidification cracking during continuous casting of slabs were analyzed. The possibility of solidification cracking during continuous casting of slabs was predicted using the "Specific Crack Susceptibility", S S C . The new proposed parameter, S S C , can represent the averaged possibility of solidification cracking of the strand during continuous casting in the mold. The surface crack formed near corner region of strand at the initial stage of solidification, and the internal crack was found in the internal regions of wide center, corner and off-corner at the middle and final stage of solidification. The carbon range sensitive to solidication cracking is between 0.1 wt% C and 0.14 wt% C steels. At the slab widths of 1 900 mm and 2 150 mm, the possibility of solidification cracking increased in the regions of wide center, corner and offcorner in comparison with the slab width of 1 600 mm. With increasing narrow face taper, the possibility of solidification cracking decreased along the region of wide face due to the mechanical compression imposed by the narrow face taper. With increasing casting speed, the possibility of solidification cracking increased in the regions of wide center, corner and off-corner, because the shell thickness is largely decreased due to decrease of dwelling time of strand within the mold. These predictions at various casting conditions were in good agreement with the experimental observations in industry.KEY WORDS: specific crack susceptibility; solidification cracking; carbon content; slab width; narrow face taper; casting speed.dency during continuous casting of steels. They divided the mushy zone into the mass/liquid feeding zone (0.4Ͻf s Ͻ0.9) and the cracking zone (0.9Ͻf s Ͻ0.99). Cracks formed in the mass/liquid feeding zone are refilled with the surrounding liquid, whereas cracks formed in the cracking zone can not be refilled with the liquid, because the dendrite arms are close enough to resist feeding of the surrounding liquid. They proposed the critical solid fraction to resist feeding of 0.9. However, the crack susceptibility coefficient can be increased with increasing carbon content, because the mushy zone increases with increasing carbon content. Many researchers 3,5,15) estimated the possibility of cracking in comparison with the maximum principal stress and transverse stress along the wide and narrow face. And, some investigators 4,16) have used a strain based fracture criterion in the mushy zone, assuming that the material fractures if the total mechanical strain exceeds 0.2% 4) and 1.6%. 16) However, the comparison of the absolute stress and strain values is not enough to investigate the possibility of cracking during continuous casting, because the stress in the solidifying shell changes as a function of temperature and the mushy zone solidifies in almost stress free state, even though the strain occurs in the mushy zone. Kelly et al. 6) and Kim et ...

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