Microsegregation of solute elements and its effect on intermediate crack of continuous casting slab
LI Maimai1, XIAO Chao2, YAN Hao1
1. Qingdao Branch of CITIC Pacific Steel Research Institute, Qingdao Special Steel Co., Ltd., Qingdao 266000, Shandong,China; 2. Automotive Research Institute, China National Heavy Duty Truck Group Co.,Ltd., Jinan 250000, Shandong,China
Abstract：Based on the regular hexahedron model proposed by Ueshima et al., and combined with the actual solidification and cooling conditions of continuous casting slab, the microscopic segregation model of solute elements was established. The segregation of solute elements at the crack origin at the end of the columnar crystal region was analyzed by using the segregation model. Considering heat transfer, static pressure of molten steel and phase transformation, the strain of solidified billet shell was simulated by finite element software to analyze the formation mechanism of intermediate crack. The results show that the segregation of phosphorus and sulfur elements at the end of the columnar crystal region is serious, and the segregation of carbon is relatively light. The difference between LIT and ZDT of the crack formation temperature increases significantly due to the segregation of elements. When the thickness of the billet is equal to the distance between the crack origin and the inner arc, that is, 85 mm, the tensile strain of the billet greatly exceeds the critical strain value allowed during the solidification of the billet, which has the external force factor of crack formation.
李麦麦, 肖超, 颜昊. 溶质元素的微观偏析及其对连铸坯中间裂纹的影响[J]. 连铸, 2023, 42(5): 57-63.
LI Maimai, XIAO Chao, YAN Hao. Microsegregation of solute elements and its effect on intermediate crack of continuous casting slab. CONTINUOUS CASTING, 2023, 42(5): 57-63.
KIM K, HAN, YEO T, et al. Analysis of surface and internal cracks in continuously cast beam blank[J]. Ironmaking and Steelmaking,1997,24 H N: 249.
[2]
KIM K H, YEO T J, OH K H, et al. Effect of carbon and sulfur in continuously cast strand on longitudinal surface cracks[J]. ISIJ International,1996,36(3): 284.
YAMANAKA A, NAKAJIMA K, OKAMURA K. Critical strain for internal crack formation in continuous casting[J]. Ironmaking and Steelmaking,1995,22: 508.
[5]
SEOL D J, WON Y M, OH K H, et al. Mechanical behavior of carbon steels in the temperature range of mushy zone[J].ISIJ International[J]. 2000, 40(4): 356.
[6]
WON Y M, YEO T J, SEOL D J,et al. A new criterion for internal crack formation in continuously cast steels[J]. Metallurgical and Materials Transactions B,2000,31:779.
[7]
WON Y M, KIM K H, YEO T J,et al. Effect of cooling rate on ZST, LIT melting point and ZDT of carbon steels near melting point[J]. ISIJ International, 1998, 38(10): 1093.
[8]
CLYNE T W, WOLF M, Kurz W. The effect of melt composition on solidification cracking of steel with particular reference to continuous casting[J]. Metallurgical Transactions B,1982,13B,259.
[9]
UESHIMA Y, MIZOGUCHI S, MATSUMIYA T, et a1.Analysis of solute distribution in dendrites of carbon steel with δ/γtransformation during solidification[J].Metallurgical and Materials Transaction B,1986,17B: 845.
[10]
WON Y M, THOMAS B G.Simple model of microsegregation during solidification of steels[J].Metallurgical and Materials Transaction A, 2001,32:1755.
HIEBLER H, ZIRNGAST J, WOLF M M. Inner crack formation in continuous casting: Stress or strain criterion[C]//1994 Steelmaking Conference Proceedings. Chicago: Iron and Steel Soc, 1994: 405.
[13]
BARRIE M. The influence of composition on the hot ductility of steels and to the problem of transverse cracking[J]. ISIJ International, 1999, 39(9): 833.
2023, Vol. 42 
