301不锈钢板坯结晶器出口热力耦合数学模型

Mathematical model of thermal-solidification and shell-stress in exit of mold of 301 stainless steel slab

针对某厂301不锈钢连铸坯表面裂纹缺陷发生率高的生产问题,建立了301不锈钢板坯连铸结晶器内凝固坯壳形成及应力和变形的热力耦合模型。该模型考虑了包晶钢高温相变特征及其结晶器内的凝固特点。利用有限元软件ANSYS,采用三维瞬态热传导有限元、生死单元技术及三维热弹塑性接触有限元算法进行求解,对301不锈钢板坯结晶器内凝固过程进行了研究。结果表明,结晶器出口处铸坯宽面中心温度最低,距角部40 mm处温度最高,坯壳最薄,随δ-Fe转变量增加,出口处坯壳温度升高,坯壳厚度变薄。铸坯宽面中心位移变形最小,角部最大,窄面位移量大于宽面。随δ-Fe转变量增加,出口处应力水平下降,热点区附近成裂指数增加,发生纹裂机率增大。

Aiming at the problem of high occurrence of surface crack defects in 301 stainless steel billet, a thermo-mechanical coupled model for the formation and stress and deformation of solidified shell in 301 stainless steel slab continuous casting mold was established. The model considered characteristic of high temperature phase change and solidification in mold of peritectic steel. The 3D transient heat conduction finite element, the element birth and death technology and the 3D thermo-elastic-plastie contact finite element method were used to solve the problem by ANSYS software. The solidification process of the 301 stainless steel slab mold was studied. The results indicate that the temperature is lowest on the center of width face of mold exit, the temperature is highest from the corner of 40 mm distance, the shell thickness is thinnest, and the shell temperature increases with the increasing of δ-ferrite transformation content at the exit, the shell thickness get thin. The displacement of slab wide face center is small, but largest in the corner; narrow surface displacement is greater than the width of face. With the increasing of δ-Fe transformation content, the level of stress decrease at the exit, the cracking index increase near the hot spot and occurrence of crack probability increases.