Macrosegregation Quality Criteria and Mechanical Soft Reduction for Central Quality Problems in Continuous Casting of Steel

Mostafa Omar El-Bealy

doi:10.4236/msa.2014.510074

Abstract

In order to study the central quality of continuously cast tool steel slabs, the simple model has been developed to simulate the macrosegregation quality criteria. The model calculates different quality criteria such as average macro-segregation level criterion “ASL”, its fluctuation level “FSL” and its segregation quality number “SQN”. These criteria are calculated based on the previous measurements of carbon and sulfur concentrations distributions in final region of spray zones and centerline area of lower and upper slab sides. The effect of mechanical soft reduction Technique “MSR” on the slab centerline quality is examined and analyzed. The model results show that MSR affects the quality of centerline areas significantly by different ways based on the casting speed. The experimental and theoretical results clarify that the qualities of different slab sides are different for all collected samples. The model results show also that the accuracy of the macro-segregation quality criteria increases quantitatively with increasing the number of analyzed segregated elements. Therefore, the macrosegregation quality criteria and their distributions can be considered as the most simple and vital tool to evaluate the various slab qualities. Finally, the mechanism of centerline segregation formation with mechanical soft reduction is discussed in this study.

Highlights

Zero defects strategy of continuous casting is fundamental for reducing production costs, processing time and to assure reproducibility of the casting operation and increase of production
All samples collected from plant trials show that the cast structure consists of mainly columnar crystals and a small equiaxed crystal zone along the centerline axis
The fraction of equiaxed crystal zone (EQZ) varies from 5% to 9% based on the operating and MSR conditions

Summary

Introduction

Zero defects strategy of continuous casting is fundamental for reducing production costs, processing time and to assure reproducibility of the casting operation and increase of production. The hard question, is how to maximize quality, minimize cost and optimize delivery To seek answers, this cannot be achieved without a quality control and a greater knowledge about the process, incorporating both operational parameters, such as components of the machine, steel composition, pouring temperature and casting metallurgical constraints such as thickness of solidified shell at the mold exit and strand surface temperature profile along the different cooling zones. Li and Thomas [7], extend the model into 2-D thermo-mechanical finite element model of thermo-mechanical behavior of solid shell in continuous casting of steel This is to avoid breakouts and the possibility to avoid interdendritic crack formation with maximization the casting speed. They concluded that the optimum mold taper was a parabolic profile

Results

Discussion

Conclusion