空心钢锭凝固过程缺陷的模拟研究

Simulation of Solidification Processes of Hollow Ingots

利用有限元软件Pro CAST对65t空心钢锭底注式凝固过程进行了数值模拟。根据实验条件和实验结果,分析确定了最终凝固位置在距离内壁35%壁厚处时的内壁界面换热系数为400 W/m2·K.采用相同的锭型、浇注方式和边界条件对4.2 t Mn18Cr18N空心钢锭进行了模拟研究,分析了不同浇注温度和浇注速度下的凝固过程。结果表明,在浇注温度为1 415℃,浇注速度为25 kg/s条件下,实现了顺序凝固,最终凝固位置在冒口内,钢锭内没有出现宏观缩孔疏松,冒口根部下方靠近钢锭内壁处存在条状的显微缩松。

The bottom filling solidification processes of a hollow ingot with 65 t weight was simulated by Pro CAST.The interface heat transfer coefficient between the core and the hollow ingot was analyzed to be 400 W/m2·K based on test conditions and result of the final solidification position located at 35% wall thickness far from the core,the solidification processes of a Mn18 Cr18 N hollow ingot with 4. 2 t weight was also simulated using the same ingot cases and gating system under the same boundary conditions. The influence of pouring temperature and pouring velocity on solidification processes has been analyzed. The results indicate that the sequential solidification and the final solidification position located at riser can be obtained at the pouring temperature of 1 415℃ and the pouring velocity of 25 kg/s. The solidification hollow ingot is free from shrinkage cavities. However,some microporosities have been observed in the hollow ingot close to internal surfaces under the root of riser.