Effect of Slow Solidification of Ultra-thick Continuous Casting Slab on Solidification Structure and Macrosegregation

Abstract

The slow solidification method of ultra-thick slab is in the ascendancy, and the macrosegregation is an important parameter of slab quality. Besides, solidification structure is also a crucial indicator of slab, such asSecondary Dendrite Arm Spacing (SDAS). In this paper, the slice moving boundary model was selected and optimized, and the influence on SDAS and macro segregation under slow solidification condition are investigated. Researches show that the SDAS increases by increasing supercooling and cooling intensity. When the superheating increases from 20 K to 40 K, the SDAS increases from 156,8 μm to 158,9 μm. By using mid-strong cooling, the segregation ratio decreases from 1,4331 to 1,3836, and the segregation degree decreases from 0,3535 to 0,3196. According to the discussions, a new method of improving the final quality of slow solidification continuous casting slabs is provided, which also has a high development prospect in the production of large-section casting slabs.

Keywords

• macro segregation
• SDAS
• solidification structure
• superheating
• ultra-thick slab