Numerical and experimental investigation of solidification structure evolution and reduction of centre segregation in continuously cast GCr15 bloom

ABSTRACT

A CAFE model and SDAS model are established in order to study evolutionary behaviour of macrostructure and secondary dendrites on 220 × 260 mm² bloom cross-section of GCr15 bearing steel, respectively. Based on numerical simulation and experiments, the effects of process parameters on centre ECR and SDAS are investigated. It is found that increase of centre ECR and decrease of SDAS occur with the decrease of superheat and with the increase of M-EMS. The results reveal that M-EMS and superheat exhibit a significant effect on centre ECR, whereas casting speed evidently affects SDAS than superheat. In addition, casting speed has the obvious influence on solidification end, which is closely related with F-EMS implementation. After less than superheat of 25°C and casting speed of 0.8 m min⁻¹ with optimized M+ F-EMS are adopted, centre ECR increases by 11% and the SDAS is effectively refined. Furthermore, centre segregation gets improved as well.

KEYWORDS:

• GCr15 bearing steel
• bloom
• centre equiaxed crystal ratio
• secondary dendrite arm spacing
• centre segregation

Acknowledgement

The authors are thankful to ZENITH Special Steel from China for the support on the field test

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The work was financially supported by the National Natural Science Foundation of China (No. 51874021) and State Key Laboratory of Advanced Metallurgy Foundation (41602014). The authors are thankful to ZENITH Special Steel from China for the support on the field test.