Thermal Elasto-plastic Stress Analysis of Solidifying Shell in Continuous Casting Mold

Kinoshita, Katsuo; Emi, Toshihiko; Kasai, Manabu

doi:10.2355/tetsutohagane1955.65.14_2022

Cited by 32 publications

(20 citation statements)

References 3 publications

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“…This approach inspired subsequent modeling studies by many others [20][21][22] . The quantitative use of stress models was not feasible in the early days, and indeed is still a challenge.…”

Section: Thermal Stress Analysis and Crack Formationmentioning

confidence: 99%

Modeling of the continuous casting of steel—past, present, and future

Thomas¹

2002

Metall Mater Trans B

134

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This lecture honoring Keith Brimacombe looks over the history, current abilities, and future potential of mathematical models to improve understanding and to help solve practical problems in the continuous casting of steel. Early finite-difference models of solidification, which were pioneered by Keith Brimacombe and his students, form the basis for the online dynamic models used to control spray water flow in a modern slab caster. Computational thermal-stress models, also pioneered by Brimacombe, have led to improved understanding of mold distortion, crack formation, and other phenomena. This has enabled process improvements, such as optimized mold geometry and spray cooling design. Today, sophisticated models such as transient and multiphase fluid flow rival water modeling in providing insights into flow-related defects. Heat flow and stress models have also advanced to yield new insights. As computer power increases and improvements via empirical plant trials become more costly, models will likely play an increasing role in future developments of complex mature processes, such as continuous casting. FORWARDIt is a great privilege to present the second ever J. Keith Brimacombe lecture at this first Electric Furnace Conference of the Third Millennium, (at least according to the Gregorian calendar). Professor Brimacombe was a giant in many fields. He also inspired many people, especially his students, including me. At the first Brimacombe lecture, last year, Indira Samarasekera [1] , gave an inspirational talk, that touched on many different facets of the research excellence that was the hallmark of this remarkable man's career. Dr. Brimacombe left a legacy of leadership, knowledge and genuine care for the people, which benefited the steel industry, the Iron and Steel Society, and many individuals here today. His technical contributions spanned a B.G. Thomas, Brimacombe Lecture,59 th Electric Furnace Conf., Pheonix, AZ, 2001, Iron & Steel Soc., pp. 3-30 4 wide range of materials engineering processes, including rotary kilns, injection, bath smelting, flash smelting, static and continuous casting, rolling, and microstructural engineering.This year's lecture will look at the history, current state, and future prospects of the mathematical modeling of the continuous casting of steel. Of the many contributions that Dr. Brimacombe gave to process metallurgy, some of his best pioneering work was done to help create this field. He was a champion of modeling and he did much to improve its credibility and usefulness, through his example. This subject is also fitting because his impact on the steel industry through short courses and publications on continuous casting made extensive use of the landmark results of his models. Indeed, he would have been the best choice to lecture on this topic, had he not suddenly left us in 1997. I am grateful to the organizers for asking me to give this lecture in an effort to continue his spirit.

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“…This approach inspired subsequent modeling studies by many others [20][21][22] . The quantitative use of stress models was not feasible in the early days, and indeed is still a challenge.…”

Section: Thermal Stress Analysis and Crack Formationmentioning

confidence: 99%

Modeling of the continuous casting of steel—past, present, and future

Thomas¹

2002

Metall Mater Trans B

134

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“…In this investigation, the elastic modulus was developed by Kinoshito 37) and the Poisson ratio was taken as constant with a value of 0.3. To correctly simulate the deformation behaviour of steel in the austenitic and ferritic phases, different constitutive behaviour is needed.…”

Section: Mechanical Propertiesmentioning

confidence: 99%

The Effect of Mould Flux Properties on Thermo-mechanical Behaviour during Billet Continuous Casting

et al. 2007

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During continuous casting mould powder forms a pool of liquid flux which infiltrates into the solidifying shell/mould gap and forms a flux film containing liquid and/or solid layers. Subsequent crystallisation of the film results in the formation of an air gap at the mould wall. An air gap can also be formed by the shrinkage of the solidified shell. In practise, no air gap is formed by shell shrinkage in the upper mould since molten flux will flow immediately into and fill any gap formed. However, in the lower mould, if the shell temperature falls below the break temperature of the flux there is no liquid to fill any gap formed by shell shrinkage and hence an air gap can form. A model was developed which determines the effect of the various layers (including the air gap) on the horizontal heat transfer between shell and mould. A fully coupled, heat transfer/stress analysis was used to calculate: (i) the thickness of the various layers of the flux film; (ii) horizontal heat flux; and (iii) the resultant stress in the solidified shell.The model predicted that: (a) the hoop stress increased as the interfacial thermal resistance decreases (i.e. the heat flux increases); (b) the maximum hoop stress at the exit decreased with increasing flux film thickness; (c) the ferro-static pressure tended to hinder the formation of an air gap at mid-face positions whereas in the corners the thicker shell tended to counteract the ferro-static pressure resulting in air gap formation; (d) the thickness of the liquid film at various positions in the mould was computed for fluxes with optimum break temperatures to determine if they provided liquid lubrication throughout the mould; and (e) the maximum stress occurred in the corner when casting with mould fluxes but at the mid-face when using oil.KEY WORDS: continuous casting; mould flux; heat transfer; finite element; stress analysis; billet; oil casting. 95© 2007 ISIJ metal. The molten flux forms a liquid pool on the top of the mould, infiltrating the mould/shell gap and partially solidifies near the mould. The flux film formed initially is glassy in nature but in time, crystallisation occurs. 17,18) Since the density of the crystalline phase is greater than that of the glass phase, crystallisation results in shrinkage of the solid flux layer and the formation of an air gap at the copper mould/flux interface. Thus the crystal/glass distribution has a significant effect on the horizontal heat transfer.A second type of air gap can also be formed by shell shrinkage. However, in the upper part of the mould liquid flux will flow into and fill any gap formed. In the lower part of the mould if the shell temperature is lower than the break temperature of the flux there will be no liquid to fill the gap (due to shell shrinkage or inadequate mould taper). Consequently an air gap can be formed under these circumstances. In this paper the air gap formed by crystallisation of the flux film is referred to as an interfacial contact resistance, whereas the air gap formed by shell shrinkage is referre...

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“…[3][4][5][6][14][15][16][17][18] Previous reports on the cracking condition in continuous casting of steels are listed in Table 1. Clyne et al 14) proposed the crack susceptibility coefficient to estimate the cracking ten-dency during continuous casting of steels.…”

Section: Introductionmentioning

confidence: 99%

“…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%.…”

Section: Introductionmentioning

confidence: 99%

“…The continuous casting process has been mathematically modeled to increase the understanding of the roles of important process variables on the defects. [2][3][4][5][6][7][8][9][10] Despite such intense studies, the thermo-mechanical behaviors of the stand and the mold during continuous casting are not fully understood due to the complex operating conditions of continuous casting process. In particular, a complexity arises in the formation of an air gap between the solidifying shell and the mold wall as a result of thermal and d/g transformation contractions.…”

Section: Introductionmentioning

confidence: 99%

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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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Thermal Elasto-plastic Stress Analysis of Solidifying Shell in Continuous Casting Mold

Cited by 32 publications

References 3 publications

Modeling of the continuous casting of steel—past, present, and future

Modeling of the continuous casting of steel—past, present, and future

The Effect of Mould Flux Properties on Thermo-mechanical Behaviour during Billet Continuous Casting

Analysis of Solidification Cracking Using the Specific Crack Susceptibility.

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