Improvement of Transverse Corner Cracks in Continuously Cast Hypoperitectic Slabs

Yasunaka, Hiroyuki; Nakayama, Kiminori; Ebina, Kiyoshi; Saito, Tadashi; Kimura, Masayasu; Matuda, Hiromu

doi:10.2355/tetsutohagane1955.81.9_894

Cited by 14 publications

(12 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…27,42) This important influence of frequency on powder consumption was also found when stroke and casting speed were kept constant.…”

Section: Effect Of Mold Oscillation Conditionsmentioning

confidence: 82%

“…Many regression equations based on powder consumption measurements in industry quantify that powder consumption decreases with higher casting speed. 7,23,27,31) Tsutsumi et al 11) found that consumption (kg m Ϫ2 ) varies inversely with casting speed if mold powder properties and oscillation conditions are kept constant. Some 32) claim that gravity is the main driving force for flux consumption, while others believe that consumption depends on interfacial frictional forces between the mold wall and shell, especially at high speed.…”

Section: Effect Of Casting Speedmentioning

confidence: 99%

“…7,11,27) Araki and ISIJ International, Vol. 46 (2006) Ikeda 28) interpret this observation with the concept of negative strip distance and propose that longer stroke and higher modification ratio should improve mold lubrication by increasing the negative strip distance.…”

Section: Effect Of Mold Oscillation Conditionsmentioning

confidence: 99%

“…1,25) Several other empirical equations have estimated the mold powder consumption as a function of various combinations of these parameters. 7,11,[26][27][28] …”

mentioning

confidence: 99%

“…Increasing stroke is predicted to decrease powder consumption very slightly, which is contrary to the trends of other researchers. 7,11,27) This disagreement may arise because oscillation stroke affects the solid slag layer velocity, and needs more study.Figure 17(b) shows the effect of oscillation frequency on mold powder consumption. Increasing frequency lowers the total consumption rate, which agrees with previous findings.…”

mentioning

confidence: 99%

See 4 more Smart Citations

Measurement and Prediction of Lubrication, Powder Consumption, and Oscillation Mark Profiles in Ultra-low Carbon Steel Slabs

et al. 2006

View full text Add to dashboard Cite

The flow of melted mold powder into the interfacial gap between the strand and the mold wall is important for productivity and quality in continuous cast slabs. Some of the mold slag (flux) consumption provides true lubrication, while much of the rest is trapped in the oscillation marks on the slab surface. This work presents measurements of powder consumption from extensive careful plant trials on ultra-low carbon steels, and a new, simple, semi-empirical model to predict slag consumption. The model predicts "lubrication consumption" by deducting the slag carried in the oscillation marks from the measured total. The oscillation mark shape is estimated from a theoretical analysis of equilibrium meniscus shape, which is based on metallographic analysis of many hook and oscillation mark shapes. The model demonstrates that the fraction consumed in the oscillation marks decreases with increasing casting speed, because the oscillation mark depth depends more on casting speed than on mold oscillation conditions. The model is validated by successful prediction of known trends of oscillation mark depth and mold powder consumption with changing various operation parameters. The model provides new insight into mold lubrication phenomena, which is important for extending casting operation to higher speeds and new lubrication regimes.KEY WORDS: continuous casting; mold powder; slag; flux; lubrication; oscillation marks; mold oscillation; stroke; frequency; modification ratio; negative strip time; positive strip time; casting speed; meniscus; models; plant experiments.ISIJ International, Vol. 46 (2006), No. 11, pp. 1635No. 11, pp. -1644 slag as shown in Fig. 1(a). The solid slag layers are glassy, crystalline, or mixtures of both 14) depending on the slag composition and local cooling rate history. [15][16][17] Several previous models of heat transfer and lubrication assume that the gap has a uniform thickness. [18][19][20] However, the real strand surface contains periodic transverse depressions called oscillation marks (OM) in Fig. 1(b). The volume of these depressions generally consumes a significant amount of slag, which greatly affects lubrication and leads to nonuniform heat transfer in the mold. 21) Thus, quantifying the oscillation mark shape is a necessary prerequisite for the prediction of lubrication and heat transfer in the mold.In this study, mold powder consumption was measured during casting trials conducted at POSCO Gwangyang Works for several different oscillation conditions and casting speeds. The measured consumptions were divided into two components: 1) the slag entrapped in the oscillation marks and 2) the remaining flux, which provides lubrication to prevent sticking, as shown in Fig. 1(b). This "lubrication consumption" is a more realistic concept to represent lubrication than total mold powder consumption.17) The oscillation mark shape is calculated by combining measured OM depths with a realistic profile based on fundamentals. 22) Correlations are found for OM depth, corresponding OM consumption, l...

show abstract

“…27,42) This important influence of frequency on powder consumption was also found when stroke and casting speed were kept constant.…”

Section: Effect Of Mold Oscillation Conditionsmentioning

confidence: 82%

Section: Effect Of Casting Speedmentioning

confidence: 99%

Section: Effect Of Mold Oscillation Conditionsmentioning

confidence: 99%

“…1,25) Several other empirical equations have estimated the mold powder consumption as a function of various combinations of these parameters. 7,11,[26][27][28] …”

mentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

Measurement and Prediction of Lubrication, Powder Consumption, and Oscillation Mark Profiles in Ultra-low Carbon Steel Slabs

et al. 2006

View full text Add to dashboard Cite

show abstract

Simulation of transverse crack formation on continuously cast peritectic medium carbon steel slabs

et al. 1999

View full text Add to dashboard Cite

Reliable data are limited to the critical strain for the formation of transverse cracks on the slabs, owing to experimental difficulty to simulate temperature gradient in solidified shell in continuous casting mold. The present study is to determine the critical strain, ɛc, for the formation of transverse cracks on continuously cast slabs. A convenient and simple hot tensile test using rectangular test pieces with either V‐notch or semi‐circle notch or oscillation marks has been developed by placing the specimen under similar temperature gradient to that in solidified shell in the mold. The ɛc has been determined at a better accuracy and reproducibility, and the ɛc at a strain rate of 5•10−4s−1 is found to be a high 35% for test pieces without notch. It sharply decreases, however, to 10% for those with V‐ and semi‐circle‐notches, slightly decreases with increasing notch depth, and further decreases for those with oscillation marks that accompany solute segregation. Reduction of the oscillation mark depth is shown to be important measure to prevent the occurrence of transverse cracking of continuously cast slabs.

show abstract

A Method to Control the Transverse Corner Cracks on a Continuous Casting Slab by Combining Microstructure Analysis with Numerical Simulation of the Slab Temperature Field

Yang

Zhang

Lai

et al. 2018

steel research int.

View full text Add to dashboard Cite

In the current article, a method based on analysis of the microstructure combined with numerical simulation of the temperature field of a continuous casting slab is proposed to eliminate the transverse cracks occurred in slab corners. The microstructures near the cracks will be varied as the phase‐transformation conditions change. Thus, the cracking temperature range can be effectively estimated by analyzing the microstructures near the cracks. The different behaviors of microstructures near cracks in three conditions are presented and discussed. These behaviors include the following: the decarburization layer is symmetrically distributed on both sides of the cracks; the microstructures are refined near the cracks; the cracks “open” the ferrite along the austenite grain boundaries, which results in the ferrite being symmetrically distributed on both sides of the cracks. The variation of the slab corner temperature during a continuous casting process is calculated and discussed. Then, a secondary cooling adjustment scheme is proposed to eliminate the occurrence of transverse corner cracks on the slab surface. Results from industrial practice show that the method can effectively avoid the generation of slab surface cracks without damage to the internal quality of the slab. The method can also be applied to other studies of crack control.

show abstract

Improvement of Transverse Corner Cracks in Continuously Cast Hypoperitectic Slabs

Cited by 14 publications

References 1 publication

Measurement and Prediction of Lubrication, Powder Consumption, and Oscillation Mark Profiles in Ultra-low Carbon Steel Slabs

Measurement and Prediction of Lubrication, Powder Consumption, and Oscillation Mark Profiles in Ultra-low Carbon Steel Slabs

Simulation of transverse crack formation on continuously cast peritectic medium carbon steel slabs

A Method to Control the Transverse Corner Cracks on a Continuous Casting Slab by Combining Microstructure Analysis with Numerical Simulation of the Slab Temperature Field

Contact Info

Product

Resources

About