Roll‐Gap Deviation on Centerline Segregation Evolution in Continuous Casting Slab

Abstract

Roll‐gap deviation (RGD) is commonly observed in the slab continuous caster, which means the thicknesses of the right and left sides are different. The RGD amounts and positions on the solute redistribution are investigated. In the RGD zone, slab thickness decreases from the left to the right side. Dynamic grid technology is used to consider the mesh deformation in the model. When RGD is set before the solidification end of the slab middle part, the center segregation in the right‐edge part decreases but that in the left‐edge part increases. That is because the solute‐enriched liquid moves from the right to the left side with solid compression. When RGD is set after the slab middle part is solidified, the center segregation in the right‐edge part is deteriorated, while that in the left‐edge part is reduced. This is because the slab right‐edge part is fully solidified in the RGD zone, and the segregation cannot be reduced in the later stage. With the RGD position moving from 15.5 to 18.0 m from the meniscus, the center segregation in the right‐edge part decreases first and then increases, while that in the left‐edge part increases slightly and then declines.

Recent advances in inclusions and central segregation control technology in tyre cord steel and saw wire steel

“…Production process and key technology Kobe Steel, Japan [43] Hot metal pretreatment → converter → LF → RH → CC (2 streams, 380 mm × 550 mm) Nippon Steel, Japan [43] Converter → LF → RH → CC (350 mm × 560 mm) Guchuan steelworks, Japan [43] 240 t converter → slag stripping → LF → CC (M-EMS and S-MES) Sumitomo Metal, Japan [43] 70 t BOF → deoxidization of silicon or silicon manganese in tapping → slag stripping → argon blowing and slag refining by VAD → CC (M-EMS and S-MES) JFE, Japan [43] L D → RH/RH + steel slag refining/argon blowing + steel slag refining → CC (400 mm × 500 mm) ThyssenKrupp, Germany [43] Desulphurization of hot metal → 140 t BOF → deoxidization of ferrosilicon alloy at tapping → RH → CC (260 mm × 330 mm, using M-EMS and S-MES) Sartre steel, Germany [43] Hot metal pre-desulphurization → 165 t BOF → RH + CASI/CAC powder → CC Blast furnace → hot metal pretreatment → LD → RH → TN powder injection → CC (125 mm × 125, 140 mm × 140 mm, EMS) Ruoert, Germany [43] √ BOF → LF → VD → CC (6 streams, 130 mm × 130 mm, forced cooling by M-EMS) Georgetown, UK [43] EAF → LF → CC (6 streams, 120 mm × 120 mm, forced cooling) Saster, UK [43] BOF → RH → CC (150 mm × 150 mm, S-EMS, F-MES forced cooling) POSCO, Korea [43] BOF → RH → MES →CC (250 mm × 300 mm) Mittal, France [44] Dephosphorization → ld-lbe → CC (360 mm × 360 mm) Unimetal, France [43] Hot metal pretreatment → LD → LBE → LF → CC (360 mm × 320 mm, M-EMS, S-EMS) Baosteel, China [43] ( √ Hot metal pretreatment → converter smelting → LF → VD → CC Pansteel, China [43] Hot metal pretreatment → converter smelting → LF → RH/AR → CC (380 mm × 280 mm) Qingsteel, China [39] 80 t BOF → slag stripping → LF → CC (6 strands, 150 mm × 150 mm) Shasteel, China [43] (1) EAF ( 90 Xingsteel, China [43] Hot metal pretreatment → BOF → LF → CC (325 mm × 280 mm) Xuansteel, China [47] Hot metal pre-desulphurization → 110 t BOF → 110 t LF → CC (150 mm × 150 mm) Tiansteel, China [48] √ Hot metal pre-desulphurization → 120 t BOF → 120 t LF → VD → CC (150 mm × 150 mm) Jiusteel, China [49] Hot metal pre-desulphurization → 60 t BOF → 60 t LF → CC (150 mm × 150 mm) Nansteel, China [43] Hot metal pretreatment → 120 t BOF → 120 t LF → CC (150 mm × 150 mm) Xingcheng Special Steel, China [43] Hot metal pretreatment → 100 t BOF → LF → RH → CC (200 mm × 200 mm, M-EMS, F-EMS, soft reduction technology)…”

“…Hot metal pre-desulphurization → ld-ob → RH + Ca treatment → IC ingot injection (2) Mould casting process: desulphurization hot metal → 300 t converter → refining → mould casting (3) CC process: scrap + hot metal → 150 t EF → refining → CC (160 mm × 160 mm) (4) CC process: scrap + hot metal → 150 t EF → refining → CC (320 mm × 425 mm) Ansteel, China [43] √ Hot metal desulphurization → converter blowing → LF → VD vacuum treatment → CC Wusteel, China [43] √ Hot metal pretreatment → converter → LF → VD/Rh → soft blowing → CC (200 mm × 200 mm) Shousteel, China [43]√ Hot metal pre-desulphurization → BOF → LF → VD → CC (130 mm × 130 mm) Xiangsteel, China[43] …”