Mn18Cr18N空心钢锭凝固缺陷与组织的模拟研究  

Simulation Research on Solidification Defects and Microstructure of Mn18Cr18N Hollow Ingots

作　　者：朱花 张博 田继红[1] 刘嘉辰 陈慧琴[1] ZHU Hua;ZHANG Bo;TIAN Jihong;LIU Jiachen;CHEN Huiqin(School of Materials Science and Engineering,Taiyuan University of Science and Technology,Taiyuan 030024,China;Aotu Personalized Education,Wuhan 430000,China)

机构地区：[1]太原科技大学材料科学与工程学院,山西太原030024 [2]武汉育人博才教育有限公司,湖北武汉430000

出　　处：《铸造技术》2020年第8期727-732,741,共7页Foundry Technology

基　　金：国家自然科学基金资助项目(51575372)。

摘　　要：对常规底注式浇注4.2 t Mn18Cr18N空心钢锭的凝固过程进行了模拟研究,分析了浇注和冷却参数对凝固缺陷和组织的影响。结果表明,内外壁的冷却条件显著影响钢锭的凝固顺序和组织特征。随着内外壁换热系数的减小,最后凝固位置移向换热系数较小的一侧,柱状晶向等轴晶的转变(CET)提前,柱状晶长度减小。在1 415 C和25 kg/s低温慢浇的条件下,当内外壁的换热系数比值为2∶5时,钢锭径向从内外壁侧向壁厚内部逐渐凝固,最终凝固位置在靠近内壁的1/4~1/3壁厚处,该处呈现一定程度的疏松缺陷,凝固组织为等轴晶;而内外壁处则为柱状晶组织,壁厚截面上两种组织比例相当。形核参数中体形核密度是影响CET以及晶粒尺寸的主要参数,而面形核密度可以控制柱状晶的一次枝晶间距。The solidification process of 4.2 t Mn18 Cr18 N hollow ingot with conventional bottom gating system was simulated, and the influence of pouring and cooling parameters on solidification defects and microstructure evolution was analyzed. The results show that cooling conditions of the inner and outer walls has intensive effect on solidification sequence and microstructure. As the heat transfer coefficient of the inner and outer walls decreases, the solidification position finally moves to the side with low heat transfer coefficient, and the transformation(CET) of columnar crystals is advanced, and the length of columnar crystals decreases. Under the condition of low temperature of 1 415 C and low pouring velocity of 25 kg/s, when the heat transfer coefficient ratio of inner and outer walls is 2 ∶5, the ingot gradually solidifies radially from the lateral wall thickness of inner and outer walls. The final solidification position is at the 1/4~1/3 wall thickness near the inner wall, where there is a certain degree of loose defects, and the solidification structure is equiaxed grains. The columnar crystal structure is found on the inner and outer wall, and the proportion of the two structures is similar on the wall thickness section. In nucleation parameters, shape nucleation density is the main parameter that affects CET and grain size, while surface nucleation density can control the primary dendrite spacing of columnar grains.

关 键 词：空心钢锭 底注式浇注 孔隙性缺陷 柱状晶 等轴晶 

分 类 号：TG244[金属学及工艺—铸造]