摘要
以Ueshima的正六边形横断面枝晶模型为原型,采用有限差分方法建立了钢凝固过程伴随δ/γ相变的两相区溶质微观偏析模型,确立了在冷却速率为10℃/s非平衡凝固条件下钢的脆性温度区间,研究分析了各溶质元素在该温度区内的偏析特点及对脆性温度区间△θ_B与热应变的影响规律,定量计算了不同P,S含量下脆性温度区热应变随C含量的变化规律.揭示了P, S含量的增加使连铸坯出现表面纵裂纹几率提高的机理.
The solidification of molten steel in continuous casting mold is a complicated nonequilibrium process with high cooling rate of 10-100 ℃/s. At such a cooling rate, the segregation of the solute elements such as C, Si, Mn, P and S in brittle temperature range （△θB） will vary with their initial contents and influence on the thermal strain significantly which could greatly increase the incidence of surface defects of strand. In this paper, a microsegregation model of solute elements in mushy zone with δ/y transformation during solidification was established based on the regular hexagon transverse cross section of dendrite shape proposed by Ueshima by finite difference method under the non-equilibrium solidification condition at 10 ℃/s of cooling rate and the brittle temperature range △θB was determined. The distribution characteristics of solute elements and the effect of their segregations on △θB and thermal strain were investigated. The results show that both P and S are the most serious segregation elements in final stage of solidification and affect on △θB significantly together with carbon content in molten steel. The mechanism that increasing contents of P and S may increase the probability of longitudinal surface crack for continuous casting strand was presented by calculating the change law of thermal strain with carbon content under different of P and S contents.
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2009年第8期949-955,共7页
Acta Metallurgica Sinica
基金
新世纪优秀人才支持计划资助项目NCET-04-0285~~
关键词
连铸
微观偏析
表面纵裂纹
脆性温度区
热应变
continuous casting, microsegregation, longitudinal surface cracks, brittle temperature range, thermal strain
