Processing parameter optimization for continuous casting of 38CrMoAl round bloom based on a prediction model of the equiaxed crystal ratio

Abstract

To control the quality of the continuous casting of 38CrMoAl round bloom, a prediction model combining the criteria of columnar to equiaxed transition, the numerical simulation of heat transfer and measured data is proposed. In this model, the inaccurate selection of heterogeneous nucleation density can be avoided. The accuracy of the numerical simulation is verified by a nail-shooting experiment, and the effects of parameters on equiaxed crystal ratio (ECR) were studied. It is proposed that low superheat and weak secondary cooling intensity increase ECR, while casting speed has little effect on ECR. The effect of strand electromagnetic stirring on the increasing ECR is clear, and it is more effective than superheat in the increasing ECR. When the diameter of the round bloom increases from 500 to 600 mm, the C_et increases from to , where ECR is larger. The suitable continuous casting parameters of ϕ500 mm bloom include a superheat of 30°C and a continuous casting speed of 0.19 m/min, as well as a weak secondary cooling intensity.

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References

Market status and development trend of continuous casting round bloom. Eng Technol. 2016;58:33–34.

Sun

Yue

Guo

et al. Mechanical properties and solidification structures of large round bloom. Steelmaking. 2016;32:66–69.

Fishburn

JH.

Seamless pipe and tubing from continuously cast steel billets. JOM. 1964;16:402–405. doi: 10.1007/BF03398118

Hunt

JD.

Steady state columnar and equiaxed growth of dendrites and eutectic. Mat Sci Eng. 1984;65:75–83. doi: 10.1016/0025-5416(84)90201-5

Shibata

Itoyama

Kishimoto

et al. Prediction of equiaxed crystal ratio in continuously cast steel slab by simplified columnar-to-equiaxed transition model. ISIJ Int. 2006;46:921–930. doi: 10.2355/isijinternational.46.921

Hou

Shan

Ting

LI.

Study on columnar to equiaxed transition of aluminium alloy. T Mater Heat Treat. 2013;34(2):120–125.

Gandin

Ch.-A

Rappaz

A coupled finite element-cellular automaton model for the prediction of dendritic grain structures in solidification processes. Acta Mater. 1994;42(7):2233–2246. doi: 10.1016/0956-7151(94)90302-6

Luo

Zhu

Louhenkilpi

Numerical simulation of solidification structure of high carbon steel in continuous casting using cellular automaton method. ISIJ Int. 2012;52:823–830. doi: 10.2355/isijinternational.52.823

Hou

Jiang

Cheng

GG.

Solidification structure and compactness degree of central equiaxed grain zone in continuous casting billet using cellular automaton-finite element method. ISIJ Int. 2012;52:1301–1309. doi: 10.2355/isijinternational.52.1301

10.

Zhao

Chen

Long

et al. Two-dimensional heat transfer model for secondary cooling of continuously cast beam blanks. Ironmak Steelmak. 2014;41:377–386. doi: 10.1179/1743281213Y.0000000164

11.

Ren

Chen

Wang

et al. Numerical simulation of fluid flow and solidification in bloom continuous casting mould with electromagnetic stirring. Ironmak Steelmak. 2015;42:401–408. doi: 10.1179/1743281214Y.0000000240

12.

Brown

SGR

Spittle

JA.

Computer simulation of grain growth and macrostructure development during solidification. Mater Sci Tech-Lond. 2013;5(4):362–368. doi: 10.1179/mst.1989.5.4.362

13.

Christian

JW.

The theory of transformations in metals and alloys. Oxford: Pergamon; 1975.

14.

Kurz

Fisher

DJ.

Dendrite growth at the limit of stability: tip radius and spacing. Acta Mater. 1981;29:11–20. doi: 10.1016/0001-6160(81)90082-1

15.

Burden

Hunt

JD.

The extent of the eutectic range. J Cryst Growth. 1974;22:328–330. doi: 10.1016/0022-0248(74)90178-X

16.

Niu

Qiu

Zhao

et al. Effects of continuous casting process parameters on carbon segregation degree of 38CrMoAl steel big round billet. J Iron Steel Res. 2018;30:359–367.